doc: Add TROUBLESHOOTING section
doc: Add TROUBLESHOOTING section

Adding this to address https://github.com/wincent/ferret/issues/1

I still want to do it, but I am not going to get to providing a helpful
hint for users who are mis-using quotes just yet. (It's just a little
hard to catch these "ERR: Error stat()ing: bar" messages in a non-kludgy
way, and I want to do it right.)

wincent/ferret