Slight update to User Defined Roles description

Make it clear that the system.users collection lives in the "admin" database, not in arbitrary databases as was true in v2.4.

Signed-off-by: Sam Kleinman <samk@10gen.com>
Update troubleshoot-replica-sets.txt

Changed 'including vitalized instances' to 'including virtualized instances'

Signed-off-by: Sam Kleinman <samk@10gen.com>