Add anchors to bullets

Every bullet is anchored with a short `<a name>` tag. This makes life easier for me at least when I want to referer people to a particular guideline, such as:

https://github.com/rapid7/ruby-style-guide/blob/add-anchors/README.md#no-and-or-or

When dealing with noobs, I want to drop them exactly on what rule I'm talking about, instead of telling them to scroll around or ctrl-F or anything like that.