RFE: Improve molecule scenarios in new collection

[cidrblock]

Add a README to the current which explains that it is there to demonstrate running exisiting integration tests with molecule.

Add an additional scenario which is 100% molecule w/o an integration test.

[jeffcpullen]

+1 on this.

Following a guide like Introducing Ansible Molecule with Ansible Automation Platform is pretty close, but will error out when actually kicking off molecule test.

➜  lab git:(main) $ cd extensions
➜  extensions git:(main) $ molecule test                                           
CRITICAL 'molecule/default/molecule.yml' glob failed.  Exiting.

There is an implied task that you need to create a directory with at least a molecule.yml that can be referenced as the scenario.

➜  extensions git:(main) $ ls molecule 
my_role  utils
➜  extensions git:(main) $ molecule test -s my_role