btrfs: update kconfig title

The Kconfig title does not make much sense after the cleanup of
CONFIG_EXPERIMENTAL option, align the wording with other filesystems.

Signed-off-by: David Sterba <dsterba@suse.cz>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
diff --git a/fs/btrfs/Kconfig b/fs/btrfs/Kconfig
index d5bfcb7..0f5374c 100644
--- a/fs/btrfs/Kconfig
+++ b/fs/btrfs/Kconfig
@@ -1,5 +1,5 @@
 config BTRFS_FS
-	tristate "Btrfs filesystem Unstable disk format"
+	tristate "Btrfs filesystem support"
 	select LIBCRC32C
 	select ZLIB_INFLATE
 	select ZLIB_DEFLATE