feat(readme): update angular version and warning

Author: Ismael Ramos

README.md

@@ -6,7 +6,7 @@
   <h3 align="center">Angular Example App</h3>
 
   <p align="center">
-    Example app with Angular 7 + Angular CLI + Angular Universal + i18n + Firebase
+    Example app with Angular 8 + Angular CLI + Angular Universal + i18n + Firebase
     <br>
     <br>
     :clap::clap::tada::tada::tada::tada::clap::clap:
@@ -96,9 +96,9 @@ This repo is using Firebase. We use Cloud Firestore and Cloud Storage to handle
 
 ## Quick start
 
-**Warning**
+<span style="color:red">**WARNING**</span>
 
-> Verify that you are running at least node 8.9.x and npm 5.x.x by running node -v and npm -v in a terminal/console window. Older versions produce errors, but newer versions are fine.
+> Verify that you are running node 12.4.0 and npm 6.x.x by running node -v and npm -v in a terminal/console window. Older versions produce errors, but newer versions are fine.
 
  ```bash
  npm i

src/i18n/messages.es.xlf

@@ -8,7 +8,7 @@
         </source><target state="final">
           Inicio
         </target>
-        
+
       <context-group purpose="location"><context context-type="sourcefile">app/shared/components/header/header.component.html</context><context context-type="linenumber">5</context></context-group></trans-unit><trans-unit id="findHero" datatype="html">
         <source>Look for a hero!</source><target state="final">Busca un heroe!</target>
         <context-group purpose="location">
@@ -84,50 +84,50 @@
         <source>
           Heroes list
         </source><target state="translated">Lista de heroes</target>
-        
+
       <context-group purpose="location"><context context-type="sourcefile">app/shared/components/header/header.component.html</context><context context-type="linenumber">8</context></context-group><context-group purpose="location"><context context-type="sourcefile">app/modules/heroes/pages/heroes-list-page/heroes-list-page.component.html</context><context context-type="linenumber">2</context></context-group></trans-unit>
       <trans-unit id="createHero" datatype="html">
         <source>Create a hero</source><target state="final">Crear un heroe</target>
-        
+
       <context-group purpose="location"><context context-type="sourcefile">app/modules/heroes/pages/heroes-list-page/heroes-list-page.component.html</context><context context-type="linenumber">46</context></context-group></trans-unit>
       <trans-unit id="create" datatype="html">
         <source>Create</source><target state="final">Crear</target>
-        
-        
+
+
       <context-group purpose="location"><context context-type="sourcefile">app/modules/heroes/pages/heroes-list-page/heroes-list-page.component.html</context><context context-type="linenumber">56</context></context-group><context-group purpose="location"><context context-type="sourcefile">app/modules/heroes/pages/heroes-list-page/heroes-list-page.component.html</context><context context-type="linenumber">89</context></context-group></trans-unit>
       <trans-unit id="nameWithPalindrome" datatype="html">
         <source>Name (Palindrome?)</source><target state="final">Nombre (Palindrome?)</target>
-        
+
       <context-group purpose="location"><context context-type="sourcefile">app/modules/heroes/pages/heroes-list-page/heroes-list-page.component.html</context><context context-type="linenumber">64</context></context-group></trans-unit>
       <trans-unit id="nameRequired" datatype="html">
         <source>
             Name is required
           </source><target state="final">
             El nombre es requerido
           </target>
-        
-        
+
+
       <context-group purpose="location"><context context-type="sourcefile">app/modules/heroes/pages/heroes-list-page/heroes-list-page.component.html</context><context context-type="linenumber">67</context></context-group><context-group purpose="location"><context context-type="sourcefile">app/modules/heroes/pages/heroes-list-page/heroes-list-page.component.html</context><context context-type="linenumber">80</context></context-group></trans-unit>
       <trans-unit id="maxLengthError" datatype="html">
         <source>
             The field is too long
           </source><target state="translated">
             El texto es demasiado largo
           </target>
-        
-        
+
+
       <context-group purpose="location"><context context-type="sourcefile">app/modules/heroes/pages/heroes-list-page/heroes-list-page.component.html</context><context context-type="linenumber">70</context></context-group><context-group purpose="location"><context context-type="sourcefile">app/modules/heroes/pages/heroes-list-page/heroes-list-page.component.html</context><context context-type="linenumber">83</context></context-group></trans-unit>
       <trans-unit id="realName" datatype="html">
         <source>Real name</source><target state="final">Nombre real</target>
-        
+
       <context-group purpose="location"><context context-type="sourcefile">app/modules/heroes/pages/heroes-list-page/heroes-list-page.component.html</context><context context-type="linenumber">77</context></context-group></trans-unit>
       <trans-unit id="errorHasOcurred" datatype="html">
         <source>An error has ocurred</source><target state="final">Ha ocurrido un error</target>
-        
+
       <context-group purpose="location"><context context-type="sourcefile">app/modules/heroes/pages/heroes-list-page/heroes-list-page.component.html</context><context context-type="linenumber">92</context></context-group></trans-unit>
       <trans-unit id="firstTwoHeroesById" datatype="html">
         <source>Heroes (1-2)</source><target state="final">Heroes (1-2)</target>
-        
+
       <context-group purpose="location"><context context-type="sourcefile">app/modules/heroes/pages/heroes-list-page/heroes-list-page.component.html</context><context context-type="linenumber">97</context></context-group></trans-unit>
       <trans-unit id="heroDetail" datatype="html">
         <source>Hero detail</source><target state="final">Detalle del heroe</target>
@@ -136,7 +136,7 @@
           <context context-type="linenumber">1</context>
         </context-group>
       </trans-unit>
-      
+
       <trans-unit id="goBack" datatype="html">
         <source>
   Go back
@@ -154,7 +154,7 @@ Volver
 </source><target state="final">
 Ancla al heroe
 </target>
-        
+
       <context-group purpose="location"><context context-type="sourcefile">app/modules/heroes/pages/hero-detail-page/hero-detail-page.component.html</context><context context-type="linenumber">13</context></context-group></trans-unit><trans-unit id="@@appTitle" datatype="html">
         <source>App title</source><target state="final">App de ejemplo de Angular</target>
         <context-group purpose="location">
@@ -168,7 +168,7 @@ Ancla al heroe
           <context context-type="linenumber">1</context>
         </context-group>
       </trans-unit><trans-unit id="@@heroesMetaDescription" datatype="html">
-        <source>Heroes meta description</source><target state="final">Lista de heroes - App de ejemplo en angular 7</target>
+        <source>Heroes meta description</source><target state="final">Lista de heroes - App de ejemplo en angular 8</target>
         <context-group purpose="location">
           <context context-type="sourcefile">src/app/app.component.ts</context>
           <context context-type="linenumber">1</context>
@@ -187,7 +187,7 @@ Ancla al heroe
         </context-group>
       </trans-unit><trans-unit id="@@heroCreated" datatype="html">
         <source>Hero created</source><target state="final">Heroe creado</target>
-        
+
       <context-group purpose="location"><context context-type="sourcefile">src/app/modules/heroes/pages/heroes-list-page/heroes-list-page.component.ts</context><context context-type="linenumber">1</context></context-group></trans-unit><trans-unit id="@@saved" datatype="html">
         <source>Saved</source><target state="final">Guardado</target>
         <context-group purpose="location">
@@ -196,7 +196,7 @@ Ancla al heroe
         </context-group>
       </trans-unit><trans-unit id="@@cannotVote" datatype="html">
         <source>Can't vote anymore</source><target state="final">No puedes votar más</target>
-        
+
       <context-group purpose="location"><context context-type="sourcefile">src/app/modules/heroes/pages/heroes-list-page/heroes-list-page.component.ts</context><context context-type="linenumber">1</context></context-group><context-group purpose="location"><context context-type="sourcefile">src/app/shared/components/hero-card/hero-card.component.ts</context><context context-type="linenumber">1</context></context-group></trans-unit><trans-unit id="@@heroRemoved" datatype="html">
         <source>Hero removed</source><target state="final">Heroe eliminado</target>
         <context-group purpose="location">