comma typos
comma typos

Signed-off-by: Sam Kleinman <samk@10gen.com>
images: fixing content of captions
Added global lock warning

This page contains enough info to not need to go and read http://docs.mongodb.org/manual/reference/command/convertToCapped/ so the warning should be present here too.

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