Add puppetcore enablement instruction

[gavindidrichsen]

Summary

This PR adds setup instruction that will work for modules or gems that require puppetcore (puppet or facter). These instructions are backward compatible. Since most repositories/modules are not yet puppetcore enabled, the pdksync should work as before; however, as more and more become linked to puppetcore then these instructions will enable the seamless operation.

Since puppet and facter are not included in either the gemspec or Gemfile, then only a doc change here is required.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 47.86%. Comparing base (8cb5725) to head (a6c2591).
Report is 2 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #227   +/-   ##
=======================================
  Coverage   47.86%   47.86%           
=======================================
  Files          10       10           
  Lines        1220     1220           
=======================================
  Hits          584      584           
  Misses        636      636           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[LukasAud]

LGTM