Follow-up from "Docs: (EE Port) Fix CI/CD related anchors"

The following discussion from !9741 (merged) should be addressed:

• @eread started a discussion:

  I think I'd given the following feedback and you'd fixed, but it might've gotten reverted.

  ../variables/README.html#predefined-environment-variables => ../variables/README.md#predefined-environment-variables

  I don't want to hold up this MR for merge.