doc: add the documentation infrastructure for pipewire modules

All empty pages for now but at least this makes them show up in the
documentation.

doc/meson.build

@@ -17,8 +17,16 @@ endforeach
 foreach h : pipewire_sources
   inputs += meson.source_root() / 'src' / 'pipewire' / h
 endforeach
+foreach h : module_sources
+  inputs += meson.source_root() / 'src' / 'modules' / h
+endforeach
 inputs += meson.source_root() / 'test' / 'pwtest.h'
 
+find = find_program('find', required: false)
+if find.found()
+
+endif
+
 # SPA headers use static inline functions. Doxygen doesn't extract those
 # unless we have EXTRACT_STATIC set - but we don't want it to extract
 # everything in the rest of the tree.
@@ -50,6 +58,7 @@ extra_docs = [
   'pipewire-design.dox',
   'pipewire-daemon.dox',
   'pipewire-library.dox',
+  'pipewire-modules.dox',
   'pipewire-tools.dox',
   'pipewire-session-manager.dox',
   'pipewire-objects-design.dox',

doc/pipewire-modules.dox

@@ -0,0 +1,40 @@
+/**
+
+\page page_pipewire_modules PipeWire Modules
+
+A PipeWire module is effectively a client provided in a `.so` file that
+shares the \ref pw_context with the loading entity. Usually modules are
+loaded when they are listed in the configuration files.
+
+A module's entry point is the `pipewire__module_init` function, see \ref
+PIPEWIRE_SYMBOL_MODULE_INIT.
+
+\code
+int pipewire__module_init(struct pw_impl_module *module, const char *args).`
+\endcode
+
+
+List of known modules:
+
+- \subpage page_module_access
+- \subpage page_module_adapter
+- \subpage page_module_client_device
+- \subpage page_module_client_node
+- \subpage page_module_echo_cancel
+- \subpage page_module_filter_chain
+- \subpage page_module_link_factory
+- \subpage page_module_loopback
+- \subpage page_module_metadata
+- \subpage page_module_portal
+- \subpage page_module_profiler
+- \subpage page_module_protocol_native
+- \subpage page_module_protocol_pulse
+- \subpage page_module_protocol_simple
+- \subpage page_module_pulse_tunnel
+- \subpage page_module_rt
+- \subpage page_module_rtkit
+- \subpage page_module_session_manager
+- \subpage page_module_zeroconf_discover
+
+
+*/