docs: filesystems: Remove uneeded .rst extension on toctables

There's no need to use a .rst on Sphinx toc tables. As most of
the Documentation don't use, remove the remaing occurrences.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

Documentation/filesystems/ext4/index.rst

@@ -8,7 +8,7 @@ ext4 Data Structures and Algorithms
    :maxdepth: 6
    :numbered:
 
-   about.rst
-   overview.rst
-   globals.rst
-   dynamic.rst
+   about
+   overview
+   globals
+   dynamic

Documentation/filesystems/index.rst

@@ -17,7 +17,7 @@ algorithms work.
    :maxdepth: 2
 
    vfs
-   path-lookup.rst
+   path-lookup
    api-summary
    splice
 
@@ -41,4 +41,4 @@ Documentation for individual filesystem types can be found here.
 .. toctree::
    :maxdepth: 2
 
-   binderfs.rst
+   binderfs