added section on python community standards

Submitted as part of my final assignment for the *Instructor training 11* course. 

I think this is very useful information for new python developers, to make them aware of these types of coding and documentation standards as they begin developing their own software. Even if students don't end up being python developers, it's useful for them to know that these types of standards exist so they can try to track them down for their programming language of choice. 

If you agree that this is useful information to include in the lessons, I'm happy to relocate, expand/reduce, etc to make it fit best with the existing lessons.