Documentation issue: warning about which user to perform which actions

[caoimhinp]

In your instructions you should probably put the warning concerning being the web user before performing fetch_changesets before the direction to perform those functions.

It will probably alleviate a few requests for help and will definitely save some of us some time. After reading it I had to go back, figure out what would break (I assume just the /tmp permissions) and then fix those issues and test.

Thank you for your time.