Update README for simple OSDU [GONRG-4287]
Minor but useful updates for README
Starting on April 8th, The Open Group will require Two Factor Authentication for all GitLab users. For instructions on setting up 2FA, see the Knowledge Article or GitLab Documentation. Note in particular that any HTTPS clones will require the use of a Personal Access Token (rather than a user’s password) once 2FA is enabled.
Minor but useful updates for README