doc: Add WpImplModule docs for the C and Lua API

docs/rst/lua_api/lua_local_module_api.rst

@@ -0,0 +1,25 @@
+ .. _lua_local_module_api:
+
+Local Modules
+=============
+
+The `LocalModule` object (which binds the :c:struct:`WpImplModule` C API) provides a way
+to load PipeWire modules in the WirePlumber process. Instantiating the object
+loads the module, and when the last reference to the returned module object is
+dropped, the module is unloaded.
+
+Constructors
+~~~~~~~~~~~~
+
+.. function:: LocalModule(name, arguments, properties)
+
+   Loads the named module with the provided arguments and properties (either of
+   which can be nil).
+
+   `name` is the module name, such as `"libpipewire-module-loopback"`.
+
+   `arguments` should be either `nil` or a string with the desired module
+   arguments.
+
+   `properties` can be nil or a table that can be :ref:`converted
+   <lua_gobject_lua_to_c>` to :c:struct:`WpProperties`.