this change enables T-Pot deployment on red hat enterprise linux. a number of hacks
had to be implemented due to RHEL's somewhat opinionated package
management mechanisms.
we also add a new section to the README which explains the caveats inherent in using RHEL.
NOTE: this change only support RHEL >= 8 due to packaging issues. it omits `grc` which depends on python2 and doesn't build on RHEL >= 7.
- Comment out Port(s) in sshd_config to avoid port conflicts when multiple SSH Port definitions present
- Resolve duplication issue for repeatedly running the install playbook
- Avoid accidental uncommenting of Port 22
