Adding compiling instructions

[Shideravan]

This may help newcomers on how to easily compile bsnes

[jchv]

Looks OK overall. I think that it would be worth considering Msys2 as a recommended path forward, though, as it is probably the most complete MinGW distribution that is well-maintained.

[Screwtapello]

Sorry it's taken me a while to look at this. I have some small and large concerns:

• Why make "bsnes" bold?
• There's already links to the git repo and Discord server under the "Links" heading, I'm not sure why you've duplicated them under the "Community" heading (and used a different Discord invite)
• You use I. and II. as list items, but Markdown doesn't recognise Roman numerals so it breaks up the flow of the list. If you just make them regular numbers but with an extra 4 spaces of indent, they should be rendered properly.
• You say "Download MinGW x64" and link to a page, but there's no actual download on that page. The page does link to a Downloads page, but that page contains nine options, none of which are titled "MinGW x64". There's a "MinGW-W64-builds" item, but it's out-of-date compared to the others and there's no way to tell whether it's too out-of-date for bsnes specifically.
• Shouldn't the MinGW installer set any required environment variables? It seems like it would be very easy for people to get this wrong, or accidentally break other things in the process. The fewer bsnes-specific instructions we have to write, and the more we can rely on generic MinGW and MSYS instructions, the better.
• Git isn't strictly-speaking required to build bsnes, so we shouldn't bring it up. If people want to use Git, there's whole websites dedicated to explaining where to get it and how to use it, so I'm happy to let those people take care of it.

[Shideravan]

Ok, I'll take all that in consideration and will rewrite the text as soon as I can

[Shideravan]

Thanks for the feedback @Screwtapello and @jchv