docs: fix various Documentation/ paths in header files

Fix various Documentation/ paths in include/linux/.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Reviewed-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/relay.h b/include/linux/relay.h
index 953fc05..14a86bc 100644
--- a/include/linux/relay.h
+++ b/include/linux/relay.h
@@ -140,7 +140,7 @@
 	 * cause relay_open() to create a single global buffer rather
 	 * than the default set of per-cpu buffers.
 	 *
-	 * See Documentation/filesystems/relayfs.txt for more info.
+	 * See Documentation/filesystems/relay.txt for more info.
 	 */
 	struct dentry *(*create_buf_file)(const char *filename,
 					  struct dentry *parent,