Specifically (I have bolded the particular section about comments only):
Posting on an external site
If you are unwilling to write a sufficient explanation to constitute a good Code Review answer, then it would be best to refrain from posting your follow-up on Code Review at all. Instead, you may host your revised code on an external site (e.g. GitHub, GitHub Gist, Pastebin, JSBin, JSFiddle, Ideone, SQLFiddle, your personal blog, etc.) Add a link to it only in a comment on the question or in a comment on the most helpful answer. Do not add it in the question or answer itself.
Although we disallow code in questions to be hosted on an external site, posting your revised code externally is fine, because:
- The primary concern of the site is make justified suggestions for improving the code. The reviews are more valuable than the final product.
- The "final" code is supplementary information that is not essential to the question-and-answer process.
- Comments are considered disposable. If the link dies, we can just delete the obsolete comment.
I feel the edit made to the question was too distracting:
Edit Feb. 15:
The code is now on Github. Contributions and pull requests are welcome.
But, I see nothing wrong with a much more modest:
The code and its updates are hosted on Github. Contributions and pull requests are welcome.
The above edit is modest, and it is "as-if" it was there from the beginning.
I propose that the policy is amended to allow "modest" links to the off-site repository. It is significant information that deserves more than just an ephemeral comment.