Replace the guidelines page with a link to the current guidelines on opendev.org.
This is a follow-up of last year's 1a11cec. It deals with links which at that point either were not present or did not support https://.
1a11cec
* Moves developer docs for AWS, ovirt, and openstack modules out of lib/ansible/, integrates them with dev_guide, with abadger's fix to make python snippets pass rstcheck
