fix/docs/languages/en/user-guide/database-and-models.rst

I was following this tutorial and ran into some errors which I discovered others had struggled with, so I thought a little clarification was in order about the location of local.php and global.php.

Edit: I get the feeling I did this fork wrong... Is it possible to retract? I think I should have started from the develop branch? I only had one change to one file... I also couldn't find a way to choose a name for the branch.