clarified instructions to explicitly add user.php

The instructions are really confusing if you have never had to add a bootstrap file or edit the bootstrap.php file.
I wrote that you should create a user.php bootstrap file and modify the bootstrap.php file to require your new file.
http://lithify.me/bot/logs/li3/2011-12-09
fixed formatting to match doc standards

Added backticks to filename and path. Removed new line at end of file.
Merge pull request #64 from oblakeerickson/patch-1

clarified instructions to explicitly add user.php