In "lib/outputcomponents.php" there's a comment at the top of the page that says:

"Please see http://docs.moodle.org/en/Developement:How_Moodle_outputs_HTML for an overview."

This URL is no longer valid. After some googling I found the new URL for the page is https://docs.moodle.org/dev/How_Moodle_outputs_HTML
 
While the page seems to be semi-obsolete, it would be preferable to have the code link to an existing page rather than to a 404. So, I'd like to submit a patch to update this URL in the code comments.