User Guide update - Database Forge

Made section levels consistent with the other database reference docs.
Added return value writeups.
Signed-off-by:James L Parry <jim_parry@bcit.ca>
Fix the user guide writeup for the DB forge
Signed-off-by:James L Parry <jim_parry@bcit.ca>
Merge pull request #3375 from jim-parry/userguide/dbforge

User Guide update - Database Forge