colored documentation syntax as comment

[aeschli]

Moved from microsoft/vscode#117388

Cloned this repo - https://github.com/JuliaLang/julia
Opened https://github.com/JuliaLang/julia/blob/3230aef393d23a75d6ad5793ca4ca2f8feb62f65/base/array.jl#L5
Looks like there is a documentation syntax with """ and I am wondering whether this should be coloured as comments

[pfitzseb]

Hm, not sure, tbh. I think both options make sense, although tokenizing these as strings would allow markdown highlighting (which we had in the past, but disabled because it tends to leak out of the string and mess up highlighting in the rest of the file).