minor symfony#10645 [Webpack Encore] Fixed code display (jmsche)

This PR was submitted for the 4.1 branch but it was merged into the 3.4 branch instead (closes symfony#10645).

Discussion
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[Webpack Encore] Fixed code display

Hi, this PR fixes an issue that renders an empty code block :)

Commits
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c58cd7a [Webpack Encore] Fixed code display

Author: javiereguiluz

frontend/encore/split-chunks.rst

@@ -50,8 +50,6 @@ The logic for *when* and *how* to split the files is controlled by the
 `SplitChunksPlugin from Webpack`_. You can control the configuration passed to
 this plugin with the ``configureSplitChunks()`` function:
 
-.. code-block:: js
-
 .. code-block:: diff
 
     Encore