On: Inferbo: Infer-based buffer overrun analyzer

[_shb]

I added some documentation on using Inferbo and other experimental checkers we are working on: http://fbinfer.com/docs/experimental-checkers.html.

All you need to do to use Inferbo is add `-a bufferoverrun` to your normal Infer command. Inferbo isn't included in 0.9.4.1, but we'll be creating a new release soon.