minor #8760 ! prefix referencing templates (silverbackdan)

This PR was squashed before being merged into the 3.4 branch (closes #8760).

Discussion
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! prefix referencing templates

#8440

Commits
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a0aec31 ! prefix referencing templates

Author: javiereguiluz

templating.rst

@@ -365,6 +365,9 @@ template living inside the AcmeBlogBundle, for example, can be overridden
 by placing a template of the same name in the ``app/Resources/AcmeBlogBundle/views/``
 directory. This gives the power to override templates from any vendor bundle.
 
+If you have overridden a template, you can use the "!" prefix to refer to the original bundle's
+template. E.g. ``@!AcmeBlog/layout.html.twig``
+
 Template Suffix
 ~~~~~~~~~~~~~~~
 

templating/overriding.rst

@@ -19,6 +19,12 @@ from the bundle to ``app/Resources/AcmeBlogBundle/views/Blog/index.html.twig``
 (the ``app/Resources/AcmeBlogBundle`` directory won't exist, so you'll need
 to create it). You're now free to customize the template.
 
+.. versionadded:: 3.4
+  
+  Instead of overridding an entire template, you may just want to override one or more blocks. You can do that by extending the original
+  template using the "!" prefix. For example:
+  ``{% extends "@!AcmeBlogBundle/layout.html.twig" %}``
+
 .. caution::
 
     If you add a template in a new location, you *may* need to clear your