Add pointer for readers to Wiki and WirePlumber docs, where the
documentation actually is at, so the configuration docs can found
starting from docs.pipewire.org
Add (minimal) reference documentation for each pipewire-pulse module.
Add some preprocessing to substitute @pulse_module_options@ in docs from
PW_KEY_MODULE_USAGE so the module options don't need to be repeated.
Produce Doxygen docs + generate manpages pipewire-pulse-modules.7,
pipewire-pulse-module-*.7
