add links to github from rubydoc.info docs in the 'github' area.

gistfile1.js

if (match = window.location.pathname.match(/^\/github\/([^\/]+\/[^/]+)\/([^/]+)/)) {
  var github_project =   match[1];
  var github_commit = match[2];

  $(".source_code").each( function() {
     if (match = $(this).find(".info.file").text().match(/^# File '([^']+)', line (\d+)/)) {
        var file = match[1];
        var line = match[2];
        
        var url = "https://github.com/" + github_project + 
                  "/blob/" + github_commit + "/" +
                  file +
                  "#L" + line;

        $(this).before(' <a href="' + url + '">[View on Github]</a>');
      } 
  });
}