A mechanism for alerting style users of version bumps

[daguar]

@phae asked me to add this. I encountered breakage recently (I had used pre-version URL implementation), so it would be good to have some system to track and alert users.

[migurski]

Thanks guys. There are three pegged versions of the style guide (0, 1, 2). They differ in small ways mostly connected to fonts. I’ll add information about this to the front page.

[migurski]

Moving forward, it's going to be mostly-correct to peg to a version for anything that's not the website, and to use root for the website.

[phae]

The pattern portfolio has now been pulled out of this repo. As such, it'll be easier to answer this issue. I've moved it to the correct repo, though. Track that if you want to follow-up. codeforamerica/pattern-library#1