message: .gitmodules: Correct name of submoduels
  Corrected name of submodules: mavlink and dronecore-proto.
diff: -[submodule "c_library_v2"]
  +[submodule "mavlink_v2"]
  path = third_party/mavlink/include/mavlink/v2.0
  url = https://github.com/mavlink/c_library_v2.git
  [submodule "gtest"]
  [submodule "tinyxml2"]
  path = core/third_party/tinyxml2
  url = https://github.com/leethomason/tinyxml2.git
  -[submodule "DronCore-Proto"]
  +[submodule "dronecore-proto"]
  path = grpc/server/proto
  url = https://github.com/dronecore/DroneCore-Proto.git
  [submodule "zlib"]
  