Update Redis repository URL to the Correct URL

[adamiBs]

This PR updates the git-repo URL to the updated location of the Redis URL.

[whalelines]

LGTM

[tianon]

We should probably also de-symlink maintainer.md and update it with more accurate text (perhaps other changes too?)

[tianon]

Doing a quick glance, another good example is the "32bit variant" section of content.md that no longer applies (as that variant no longer exists).

[adamiBs]

I'll create a PR for that (I'll consult with peers on updated docs in general, since we could update other sections too).