Re: Nim Compiler Documentation

[timothee]

compiler docs used to be generated for a short while until 
[https://github.com/nim-lang/Nim/pull/13509](https://github.com/nim-lang/Nim/pull/13509);
 a few small things need to be addressed to re-enable compiler docs, which was 
quite helpful, eg for nim-lang.github.io/Nim/compiler/ast.html (link doesn't 
work anymore)