Fix a typo

Author: javiereguiluz

components/filesystem.rst

@@ -327,7 +327,7 @@ when passing the path to a directory instead of a file::
 
     $contents = $filesystem->readFile('/some/path/to/file.txt');
 
-The ``$contents`` variable now stores all the contents of the ``filex.txt`` file.
+The ``$contents`` variable now stores all the contents of the ``file.txt`` file.
 
 Path Manipulation Utilities
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