php-src docs

Hi everyone. I would like to start an initiative to centralize documentation of the PHP internals. As mentioned in a recent e-mail, there's a lot of useful documentation scattered across the internet, like the PHP internals book, various blogs of contributors, wiki.php.net, to name a few. Information is currently hard to discover over multiple mediums. Some of these mediums are also prone to go stale and can't be updated by internals (e.g. blog posts). After a brief discussion at the foundation, we think it's best to incorporate the documentation directly into the php-src repository. This makes it very easy to discover, contribute to, and allows updating documentation right alongside its technical changes. To make browsing the documentation easier, the documentation is built with Sphinx and published to GitHub Pages. I've prepared a PR here: https://github.com/php/php-src/pull/13338 https://iluuu1994.github.io/php-src/ (will be moved to php.github.io once merged) Let me know of any thoughts and suggestions you might have. Ilija