minor #13839 Update filesystem.rst (zairigimad)

This PR was submitted for the 5.0 branch but it was merged into the 3.4 branch instead.

Discussion
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Update filesystem.rst

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Commits
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eb3f718 Update filesystem.rst

Author: javiereguiluz

components/filesystem.rst

@@ -193,6 +193,8 @@ of a single file or directory::
     $filesystem->rename('/tmp/processed_video.ogg', '/path/to/store/video_647.ogg');
     // renames a directory
     $filesystem->rename('/tmp/files', '/path/to/store/files');
+    // if the target already exists, a third boolean argument is available to overwrite.
+    $filesystem->rename('/tmp/processed_video2.ogg', '/path/to/store/video_647.ogg', true);
 
 ``symlink``
 ~~~~~~~~~~~