This commit appends the README.md to state that yaml files should start
with `---` and end with `...`. This also addresses some linting
warnings that were not appearing during pre-commit on local system.
In this push, we are making a decent amount of updates to the gitlab
playbooks as well as updating the README. See below for the changes:
* README updated for further clarity
* GitLab role with further reconfiguration for group lookups
* GitLab role with further reconfiguration to disable built-in nginx
* nginx configuration added and provided to work with omnibus
* GitLab variables updated