Sharpmake Documentation Task

[Sharlock93]

Hello,
As I want to start to help with documenting Sharpmake, I wanted a place to put in tasks to track.
I know I could have created issues, and I might still do that but I wanted to open up some discussion and ideas first.
Using #414 as the starting point and continuing the discussion. I had these steps in mind, roughly:

• Pick a tool for the documentation.
• Simple example that covers the basics. Main, Solution, Project, Config, Target, Options.
• Document Project class.
• Document Project Configuration.
• Document Solution class.
• Document Solution Configuration.
• Document Target class.
• Document other sharpmake includes.
• Document Platform extension (NDA Platforms info)
• Document use of FastBuild
• Advanced example which includes more than one build system, platform, using FastBuild etc.
• Document Options.
• Document Global Options.
• Document other Generators like JsonCompileCommands

I have already started work on the first point, first thing came to mind was DocFx which is from microsoft.
Done nothing beyond just set it up and point it to the sharpmake files, we already have something like this:

which seems really nice as most of the sharpmake code has documentation but not easy to access by users.
I will try to dig more into the tool this coming week to see what configs there are.
Not sure if this is better as a separate repo entirely or if this is even the correct approach.
On one hand it would be nice if the docs were in the same repo, on the other having them be separate makes it easier to work with.
DocFx also supports PDF generation which is nice.

I have my won Trello-like clone for my own Todo list, not sure what the preference here is (maybe just issues).

Any feedback/input is welcomed.

[jspelletier]

see #455