[clang-doc] --repository links don't work with github

[danakj]

The generated links are of the form https://repository/path.h#22

However github requires the URL fragmment to be L22 not 22, so it should be https://repository/path.h#L22

A configuration option to adjust the url fragment would be appreciated.

[hulxv]

@ilovepi Can I be assigned to this issue? Please give me more details about it also.

[hulxv]

As I read in 1a7e79b, we can parse the URL of the repo and detect if it's a host that has a prefix or not, such as GitHub or Gitlab (they also use L letter for lines as github). Is my approach correct?