⚡️ Drop docs generation in fdo interfaces

These are well-known and documented (in the spec itself) and need not be
documented in the introspection XML. Combined with similar changes in
zbus, this reduces our release binary's size by 200KB.

src/fdo/dbus.rs

@@ -60,7 +60,7 @@ impl DBus {
     }
 }
 
-#[interface(interface = "org.freedesktop.DBus")]
+#[interface(interface = "org.freedesktop.DBus", introspection_docs = false)]
 impl DBus {
     /// This is already called & handled and we only need to handle it once.
     async fn hello(

src/fdo/monitoring.rs

@@ -28,7 +28,10 @@ impl Monitoring {
     }
 }
 
-#[interface(interface = "org.freedesktop.DBus.Monitoring")]
+#[interface(
+    interface = "org.freedesktop.DBus.Monitoring",
+    introspection_docs = false
+)]
 impl Monitoring {
     async fn become_monitor(
         &self,