docs(i18n): apply guidelines and update TOCs

Author: kapunahelewong

public/docs/_examples/cb-i18n/ts/src/app/app.component.html

@@ -4,14 +4,14 @@ <h1 i18n="User welcome|An introduction header for this sample">Hello i18n!</h1>
 <!--#enddocregion i18n-attribute-meaning-->
 
 <!--#docregion i18n-ng-container-->
-<ng-container i18n>I don't output any element</ng-container>
+<ng-container i18n>I don't output an element</ng-container>
 <!--#enddocregion i18n-ng-container-->
 
 <br />
 
 <!--#docregion i18n-with-comment-->
 <!--i18n: optional meaning|optional description -->
-I don't output any element either
+I don't output an element either
 <!--/i18n-->
 <!--#enddocregion i18n-with-comment-->