Revert "[#7939] revert some changes (revert them for 3.2)"

This reverts commit 32c72bd.

Author: xabbuh

reference/twig_reference.rst

@@ -567,14 +567,18 @@ file_excerpt
 
 .. code-block:: twig
 
-    {{ file|file_excerpt(line) }}
+    {{ file|file_excerpt(line, srcContext = 3) }}
 
 ``file``
     **type**: ``string``
 ``line``
     **type**: ``integer``
+``srcContext`` *(optional)*
+    **type**: ``integer``
 
-Generates an excerpt of a code file around the given ``line`` number.
+Generates an excerpt of a code file around the given ``line`` number. The
+``srcContext`` argument defines the total number of lines to display around the
+given line number (use ``-1`` to display the whole file).
 
 format_file
 ~~~~~~~~~~~