bpo-24937: Replace the extension module porting HOWTO by links to external projects by encukou · Pull Request #9317 · python/cpython
I've talked with Benjamin, and he's OK with just removing the "Porting Extension Modules to Python 3" HOWTO, and replacing it by links to external guides that do a much better job at documenting this.
Also, Python 2.6 and 3.0 is EOL; it should be fine to scrub capsulethunk.