Fix include doc

This "include" is not working.
See http://docs.mongodb.org/manual/tutorial/add-user-to-database/

I'm pretty sure it's because it's too close to the line above (looking at the other "include"(s) in other docs)

Signed-off-by: Sam Kleinman <samk@10gen.com>
minor: tweaking list of links to fit with the new list idiom