Added comment to adminlib.go

Change-Id: I89945baffe18fe2747ea214466fc823b2af7dcf4
Reviewed-on: http://review.couchbase.org/40898
Reviewed-by: Pratap Chakravarthy <prataprc@couchbase.com>
Tested-by: Pratap Chakravarthy <prataprc@couchbase.com>