Add more documentation to project webpage

[justinlubin]

Add a project webpage that explains how to use Smyth in very friendly terms (with download and installation instructions).

This webpage would ideally include a tutorial of building a program using Smyth, preferably a non-trivial one (even if each use of Smyth is no bigger than the ones in the ICFP publication). For example, the tutorial could be about how to use Smyth to build up something from CMSC 22300 at UChicago.

[justinlubin]

There's now a website live at https://uchicago-pl.github.io/smyth/, but it would be great to have more documentation and step-by-step instruction of how to use Smyth (especially the CLI).