Make it easier to get started adjusting PEP8

I added quick start guide how to adjust pep8 settings. This will make SublimeLinter-pep8 more friendly towards new users who might have hard time to find how the settings work through all Sublime Text and SublimeLinter settings layers.
@miohtama Yes. I could change the files myself, but I would like you to get the credit for the idea at least.