docs: Use the kerneldoc comments for memalloc_no*()

Now that we have kerneldoc comments for
memalloc_no{fs,io}_{save_restore}(), go ahead and pull them into the docs.
Signed-off-by: NJonathan Corbet <corbet@lwn.net>

Documentation/core-api/gfp_mask-from-fs-io.rst

@@ -33,6 +33,11 @@ section from a filesystem or I/O point of view. Any allocation from that
 scope will inherently drop __GFP_FS respectively __GFP_IO from the given
 mask so no memory allocation can recurse back in the FS/IO.
 
+.. kernel-doc:: include/linux/sched/mm.h
+   :functions: memalloc_nofs_save memalloc_nofs_restore
+.. kernel-doc:: include/linux/sched/mm.h
+   :functions: memalloc_noio_save memalloc_noio_restore
+
 FS/IO code then simply calls the appropriate save function before
 any critical section with respect to the reclaim is started - e.g.
 lock shared with the reclaim context or when a transaction context