Update documentation for Solver Setup

[suargi]

Update the documentation of Solver-Setup.md

The idea is to make divide #59 into small pull requests in order to make things smoother and easier. This one addresses only the Solver-Setup.md.

~~There is documentation for certain fields still missing, e.g., SST_OPTIONS. I am not sure about each of them. I will work on that.~~ Done.

~~There seems to be some problem with markdown-latex that I cannot solve. I will work on that.~~ Something is odd. In my local machine everything works fine.