Merge pull request #3750 from Kagami/docs-fs-typo

Add missed type to FS.mount docs

site/source/docs/api_reference/Filesystem-API.rst

@@ -131,7 +131,7 @@ File system API
 
 	Mounts the FS object specified by ``type`` to the directory specified by ``mountpoint``. The ``opts`` object is specific to each file system type.
 
-	:param type: The :ref:`file system type <filesystem-api-filesystems>`: ``MEMFS``, ``NODEFS``, or ``IDBFS``.
+	:param type: The :ref:`file system type <filesystem-api-filesystems>`: ``MEMFS``, ``NODEFS``, ``IDBFS`` or ``WORKERFS``.
 	:param object opts: A generic settings object used by the underlying file system. 
 	
 		``NODFES`` uses the `root` parameter to map the Emscripten directory to the physical directory. For example, to mount the current folder as a NODEFS instance: