Replace 'Puppet master' with 'OpenVox Server' across 8x docs

[miharp]

Summary

Many pages in the 8x docset still use "Puppet master" (the old product name) where "OpenVox Server"
is the correct term. This is a broad rename pass across the collection.

Scope

Files with the most occurrences (identified during #222 review):

• quick_start_master_agent_communication.markdown — title + 10+ occurrences
• ssl_autosign.markdown — ~14 occurrences, plus lingering PE monolithic/split references on lines 24–25
• subsystem_agent_master_comm.markdown — ~14 occurrences
• config_important_settings.markdown — ~8 occurrences
• dirs_ssldir.markdown — ~8 occurrences
• dirs_confdir.markdown — ~7 occurrences (including "Master only" labels)
• dirs_vardir.markdown — ~4 occurrences
• config_print.markdown — section heading + 3 occurrences

Notes

• [master] config section in puppet.conf, --section master, and setting names like
  jruby-puppet.master-conf-dir are correct technical terms — do not change.
• master.example.com hostname examples can stay or be updated to server.example.com at discretion.
• Rack application notes can be removed where they appear (Rack/Passenger master is long deprecated).