Changes:
- Use `.Dq Li` for inline commands.
- Move references to handbooks to the //SEE ALSO// section.
- Use `Rs` macros to reference handbooks.
- Reference pkg(8) is not installed by default. pkg(7) is. Reference pkg(7) first and then pkg(8) in additional documentation.
- Fix `file` URIs (use `file:///absolute/path` instead of `file:/absolute/path`).