message: Update hello_world.cpp
  Simple typo
diff: @@ -21,7 +21,7 @@ TEST(HelloWorld, SayHello)
  std::vector<uint64_t> uuids = dl.device_uuids();
  EXPECT_EQ(uuids.size(), 1);
  - // Appearantly it can say hello.
  + // Apparently it can say hello.
  dl.device().example().say_hello();
  sitl::stop();
  