Add example implementation to prepare/install roles

[Tompage1994]

The roles don't really have an obvious example to follow for installing AAP.

In particular it isn't obvious what needs to be set for aap_setup_prep_inv_nodes and aap_setup_prep_inv_vars. The readme does point to the defaults but that isn't really documentation.

Just adding to the example at the bottom of the prepare and install roles' readmes would be a good start here.

add something like:

...
vars:
  aap_setup_prep_inv_nodes:
    automationcontroller:
      autoctl1.example.com: 
      autoctl2.example.com: 
  aap_setup_prep_inv_vars:
    ...