message: Add missing documentation string
diff: @@ -978,6 +978,7 @@ struct EventBookmark
  DECLARE_REFLECTION_STRUCT(EventBookmark);
  +DOCUMENT("Controlling interface for interop with RGP tool.");
  struct IRGPInterop
  {
  DOCUMENT(R"(Return true if the given :data:`eventId <renderdoc.APIEvent.eventId>` has and
  