Add @a2lix/symfony-collection solution

Author: webda2l

form/form_collections.rst

@@ -747,13 +747,17 @@ the relationship between the removed ``Tag`` and ``Task`` object.
     updated (whether you're adding new tags or removing existing tags) on
     each Tag object itself.
 
-.. sidebar:: Form collection jQuery plugin
+.. sidebar:: Form collection external solutions
 
     The jQuery plugin  `symfony-collection`_ helps with ``collection`` form elements,
     by providing the JavaScript functionality needed to add, edit and delete
     elements of the collection. More advanced functionality like moving or duplicating
     an element in the collection and customizing the buttons is also possible.
+    
+    The package `@a2lix/symfony-collection`_ helps as well with ``collection`` form elements,
+    to provide to modern browsers a simple version that do not require jQuery anymore.
 
 .. _`Owning Side and Inverse Side`: http://docs.doctrine-project.org/en/latest/reference/unitofwork-associations.html
 .. _`JSFiddle`: http://jsfiddle.net/847Kf/4/
 .. _`symfony-collection`: https://github.com/ninsuo/symfony-collection
+.. _`@a2lix/symfony-collection`: https://github.com/a2lix/symfony-collection