message: pkgconfig: add missing include directory
diff: @@ -8,4 +8,4 @@ Description: API and library for MAVLink compatible systems written in C++17
  Version: @MAVSDK_VERSION_STRING@
  Requires.private: libcurl jsoncpp tinyxml2
  Libs: -L"${libdir}" -lmavsdk
  -Cflags: -I"${includedir}"
  +Cflags: -I"${includedir}" -I"${includedir}/mavsdk"
  