Add Stan to Haskell static code analysis software

[chshersh]

Stan is a Haskell static analysis tool. It uses a novel approach for static analysis (the algorithm is based on HIE files). And the tool provides various code analysis and suggestions.

You can find more info about Stan in README:

• https://github.com/kowainik/stan#stan

I've discovered a list of Haskell static tools in here, and I think that Stan would be a great fit for this list 🙂