Changed the hyperlink in README.md and HACKING.md to correctly reflec…

[JTM-UofL]

Changed the hyperlink in README.md and HACKING.md to correctly reflect the sphinx webpage

[jsquyres]

Thanks!

[jsquyres]

@JTM-UofL Could you make a corresponding PR to the v5.0.x branch?

The changes will be essentially the same, but should cite the v5.0.x documentation URLs, not the main branch documentation URLs.

We usually cherry-pick to the v5.0.x release branch, but I think that since the 2 changes will not be the same as the commits on the main branch, you can't really cherry pick. So the commit message should likely cite something to the effect that this is the analogous change to commit 48883b7 on main, but updates the v5.0.x URLs, not the main branch URLs.

Also, in the body of the PR description to the v5.0.x branch, include "bot:notacherrypick" on a line by itself to tell our CI checker that this is intentionally not a cherry pick, and that that's ok.

Thank you!