Add legacy docs variable compatibility shim

[miharp]

Summary

Adds a small Jekyll plugin that restores the simple inherited Puppet docs variables during rendering, and fixes the remaining Hiera references directly in the six affected OpenVox markdown pages.

The plugin now only injects puppet, puppetserver, puppetdb, and facter into the Liquid render payload. Hiera links are direct source edits. PE-specific links/callouts are intentionally left out of scope for a future PR.

Why

The inherited Puppet docs source still uses bare Liquid variables like {{puppetserver}}, {{facter}}, and {{puppetdb}}. In this site they are undefined, so Jekyll renders them as empty strings and produces broken links such as /services_master_puppetserver.html.

Hiera references only appear in six source files, so those were fixed directly and made markdownlint-clean. The generated type docs remain untouched for #114.

Fixes #115.

Validation

• bundle exec jekyll build
• git diff --check
• npx --yes markdownlint-cli2 docs/_openvox_8x/lang_summary.markdown docs/_openvox_8x/lang_node_definitions.markdown docs/_openvox_8x/lang_classes.markdown docs/_openvox_8x/hiera_config_yaml_3.md docs/_openvox_8x/system_requirements.markdown docs/_openvox_8x/services_commands.markdown
• Confirmed no rendered {{puppetserver}}, {{facter}}, {{puppetdb}}, {{puppet}}, or {{hiera}} variables remain under _site/openvox/latest or _site/openvox/8.x
• Confirmed /openvox/latest/services_commands.html renders fixed Puppet Server, Facter, and Hiera links

Rollback note

The first commit (e30528bf9) is the plugin-only rollback point. The second commit (95693cbb6) contains the direct Hiera markdown edits and lint cleanup.