Document a policy about fishing expeditions

Summary:
Tighten the Phabricator support policy from "we will help with literally anything for free" to "we will help with anything for free, except unreproducible fishing expeditions".

This is not the right policy in the long term (in some form, I expect the level of free support will decrease, and, e.g., I won't be offering to drive to your place and fix your stuff), but this class of issue is by far the worst and most pressing and I want to stop dealing with fishing expeditions like this one right now, since I hate supporting them and they're a disproportionately huge waste of time:

https://github.com/facebook/phabricator/issues/233

We had a similar case over the weekend on Facebook:

(... snip many messages ...)
Adam Aahil
:(
need your help bro i have to also setup on live server as well
still trying ...
not success
after doing this my local apache is not restarting ..

Adam Aahil
when u get time plz let me know

Write a friendly explanation of why these support cases aren't a priority and how to build repro cases.

If this looks good, I plan to respond to anything that I can't reproduce in a few minutes with a link to this.

Test Plan: {F24759}

Reviewers: btrahan, chad

Reviewed By: chad

CC: vrana, aran

Differential Revision: https://secure.phabricator.com/D3981