quick fix. Added readonly property to common on mdInput

Author: pablohpsilva

docs/src/pages/components/Input.vue

@@ -161,7 +161,7 @@
             <form novalidate @submit.stop.prevent="submit">
               <md-input-container>
                 <label>Initial value</label>
-                <md-input v-model="initialValue"></md-input>
+                <md-input v-model="initialValue" readonly></md-input>
               </md-input-container>
 
               <md-input-container>

src/components/mdInputContainer/common.js

@@ -9,7 +9,8 @@ export default {
     required: Boolean,
     maxlength: [Number, String],
     name: String,
-    placeholder: String
+    placeholder: String,
+    readonly: Boolean
   },
   data() {
     return {

src/components/mdInputContainer/mdInput.vue

@@ -7,6 +7,7 @@
     :required="required"
     :placeholder="placeholder"
     :maxlength="maxlength"
+    :readonly="readonly"
     @focus="onFocus"
     @blur="onBlur"
     @input="onInput"