Fixes #614 - remote URL not working for wiki links

[jeffslofish]

Description

Fixes #614 - remote URL not working for wiki links

This only fixes the remote URL for GitHub wikis. If there are additional providers that use wikis that we want to support then those will need to be added.

Checklist

• I have followed the guidelines in the Contributing document
• My changes follow the coding style of this project
• My changes build without any errors or warnings
• My changes have been formatted and linted
• My changes include any required corresponding changes to the documentation (including CHANGELOG.md and README.md)
• My changes have been rebased and squashed to the minimal number (typically 1) of relevant commits
• My changes have a descriptive commit message with a short title, including a Fixes $XXX - or Closes #XXX - prefix to auto-close the issue that your PR addresses

[eamodio]

@jeffslofish Thanks for this, but unfortunately there seems to be a lot more needed than just converting .wiki to /wiki -- in my quick testing, revision URLs need to be reformatted form .wiki/blob/<sha>/<wiki-file-name>.md to /wiki/<wiki-file-name>/<sha>. There also doesn't seem to be a URL to get to a wiki commit, branch, etc.

[eamodio]

See main comment