Fix minor typo in UserPassPair comment.
Fix minor typo in UserPassPair comment.

Change-Id: I31e2d4e17837c5e2e0ef88e23e77dda5cee913f4
Reviewed-on: http://review.couchbase.org/87331
Reviewed-by: Brett Lawson <c8c4369773d7d7226e031f0c4af62e3f38a08510@gmail.com>
Tested-by: Brett Lawson <c8c4369773d7d7226e031f0c4af62e3f38a08510@gmail.com>

brett19/gocbcore