issue #827 max characters alert

sails/src/assets/scripts/modules/student/views/pictoconfig.html

 <div id="picto_config">
+
     <div class="modal-header">
         <button type="button" class="close" ng-click="close()">
           <span aria-hidden="true">&times;</span><span class="sr-only" translate>close</span>
         </button>
         <h4 class="modal-title" id="myModalLabel" translate>pictogram_setup</h4>
     </div>
+
     <div class="modal-body">
+        <div class="container-fluid">
+
           <div class="form-group">
+            <div class="row">
               <label translate>expression</label>
+            </div>
             <!-- Modificable sólo si es el propietario del picto -->
-        <div id="add_label" class="input-group">
+            <div class="row">
+              <div class="col-xs-6">
+                <div class="input-group" id="add_label" >
                   <span class="input-group-addon glyphicon glyphicon-comment" aria-hidden="true"></span>
                   <input type="text" class="form-control" ng-model="studentPicto.attributes.expression" />
                 </div>
               </div>
+              <div class="col-xs-6">
+                <div class="alert alert-info" style="margin: 0 auto;">
+                  <strong>¡Atención!</strong> La expresión debe tener un máximo de 8-10 caracteres.
+                </div>
+              </div>
+            </div>
+          </div>
 
           <div class="form-group">
             <label translate>legend</label><br/>
@@ -48,7 +63,8 @@
               <button class="btn btn-secondary margin-right10 pull-right" ng-click="close()" translate>cancel</button>
             </div>
           </div>
+
       </div>
     </div>
-    <!-- End modal-body -->
+
 </div>