message: README: fix example instructions
diff: @@ -31,7 +31,15 @@ The library provides both synchronous (blocking) API calls, as well as asynchron
  Check out the [example](example/). It sets up a UDP connection, waits for a device appearing, and commands it to takeoff and land again, while receiving some telemetry.
  -To build and try it, start PX4 in SITL and do on the same machine:
  +To build and try it, start PX4 in SITL and build and run the example as follows:
  +
  +Build and install the DroneLink library first:
  +
  +```
  +make default install
  +```
  +
  +Then build the example:
  ```
  cd example/
  