Documentation: add makefiles for more targets

Add a bunch of previously unbuilt source files to the Documentation build
machinery.

Signed-off-by: Peter Foley <pefoley2@pefoley.com>
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/Documentation/filesystems/Makefile b/Documentation/filesystems/Makefile
index 883010c..13483d1 100644
--- a/Documentation/filesystems/Makefile
+++ b/Documentation/filesystems/Makefile
@@ -1,3 +1,5 @@
+subdir-y := configfs
+
 # List of programs to build
 hostprogs-y := dnotify_test