Licensing issues may arise from shared code snippets or even full packages. While the site itself can be safely licensed under Creative Commons, individual package documentation would remain under the author's own licensing terms according to their license file/file header etc. For general site content and contributed code snippets, I lean toward the Attribution-ShareAlike license as it allows commercial use but requires attribution to the original site/author as well as licensing any derivatives under the same terms. I'm fairly open in this regard in that I feel only a derivative code block should be ShareAlike CC-licensed instead of the whole work (unless the whole package is based on a shared code snippet, that is!).
To publish a GH hosted site, we only need to commit an index.html file (+CSS/JS/IMG if not using a CDN) to a repo named sublimetext.github.com. I can see one has already been made so that's not a problem. What I suggest for package documentation is to have a basic predefined template in a "gh-pages" branch. An author wishing to contribute their own documentation may be added to the SublimeText organisation so they can create their own "gh-pages" branch, or they can fork the template and submit a pull request. The 2nd option is my recommendation for quality control and security.
I prefer Markdown for documentation as it's well supported by github and a little easier (semantically) than Sphinx. I also quite like the online tool
to convert to HTML, making it less complicated to build.