bug: Docs and vendored regexes don't work on windows

[ianlewis]

Copied from here: ianlewis#1

Regexes in the generated documentation.yml and vendor.yml include *nix path separators which won't match windows paths.

[ianlewis]

From here: ianlewis#1 (comment)

and it's getting me wondering: is there ever a scenario where path separator is part of the filename passed to linguist? How can I test this actually does anything cause right now it's not ._.

It doesn't seem to be an issue for language detection but for the IsVendored and IsDocumentation functions.

IIUC the regexes generated in the documentation.yml or vendor.yml have a (^|/) prefix which allow them to match a full file path like vendor/package/foo.go or foo.go but this doesn't work in the case of windows paths.

@dayvonjersen