Align markdown headers

A fairly trivial change since `Role Name` and `Example Playbook`
will likely be modified anyways.  However, since all the other
sections are aligned properly, felt it would be nice to "clean this up".

Before:

    Role Name
    ========

    Example Playbook
    -------------------------

After:

    Role Name
    =========

    Example Playbook
    ----------------
Merge pull request #8185 from retr0h/retr0h/align-markdown-headers

Retr0h/align markdown headers