update wording: use custom alias to be opposed to random alias

app/dashboard/templates/dashboard/custom_alias.html

@@ -9,7 +9,7 @@
 {% block default_content %}
   <div class="card">
     <div class="card-body">
-      <h1 class="h3">New Email Alias</h1>
+      <h1 class="h3">New Custom Alias</h1>
 
       {% if  user_custom_domains|length == 0 and not DISABLE_ALIAS_SUFFIX %}
         <div class="row">

app/dashboard/templates/dashboard/index.html

@@ -71,7 +71,7 @@
           <input type="hidden" name="form-name" value="create-custom-email">
           <button data-toggle="tooltip"
                   title="Create a custom alias"
-                  class="btn btn-primary mr-2"><i class="fa fa-plus"></i> New Email Alias
+                  class="btn btn-primary mr-2"><i class="fa fa-plus"></i> New Custom Alias
           </button>
         </form>
         <div class="btn-group" role="group">