Clean up documentation on compilation

[mgunyho]

This is resolves #408.

I removed some duplicate information across the documentation related to compilation. Here are markdown files corresponding to wiki pages with some changes.

• I removed all detailed compilation instructions from the main README and build/README.md and made them link to the wiki instead.
• I changed links saying "for detailed instructions, see build/README" to point to the wiki
• The first part of the compilation section in the manual is left mostly intact (so there is a bit of duplicate info), but I removed the more advanced instructions and added links to the wiki.
• The MSVC/MSYS2 specific instructions are still in build, I added links to those in the wiki pages
• There was a section 'Notes regarding the backends compilation' in the build/README that wasn't in the wiki, I added it to the backends wiki page. Not sure how relevant or up to date it is.
• I also added some small changes to the embedding manual page

I tried to make sure that everything that was removed from the MD's is in the wiki files.

I'm not that familiar with CMake so if you find any mistakes, please feel free to correct them.

[dfober]

That's fine! Thanks!