docbook: add idr/ida to kernel-api docbook

Add idr/ida to kernel-api docbook.
Fix typos and kernel-doc notation.

Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Naohiro Aota <naota@elisp.net>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/idr.h b/include/linux/idr.h
index 928ae71..13a801f 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -81,6 +81,7 @@
 #define _idr_rc_to_errno(rc) ((rc) == -1 ? -EAGAIN : -ENOSPC)
 
 /**
+ * DOC: idr sync
  * idr synchronization (stolen from radix-tree.h)
  *
  * idr_find() is able to be called locklessly, using RCU. The caller must