dm thin: extend thinpool status format string with omitted fields

Signed-off-by: mulhern <amulhern@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

Documentation/device-mapper/thin-provisioning.txt

@@ -276,7 +276,8 @@ ii) Status
 
     <transaction id> <used metadata blocks>/<total metadata blocks>
     <used data blocks>/<total data blocks> <held metadata root>
-    ro|rw|out_of_data_space [no_]discard_passdown
+    ro|rw|out_of_data_space [no_]discard_passdown [error|queue]_if_no_space
+    needs_check|-
 
     transaction id:
 	A 64-bit number used by userspace to help synchronise with metadata