message: README: install instructions
diff: @@ -27,6 +27,20 @@ The library provides both synchronous (blocking) API calls, as well as asynchron
  - [mission](plugins/mission/mission.h)/[mission_item](plugins/mission/mission_item.h): to upload a waypoint mission
  - [offboard](plugins/offboard/offboard.h): for velocity or position control
  +## Install artefacts
  +
  +The build artefacts (headers and static library file) can be installed locally into the folder `./install/` using:
  +
  +```
  +make default install
  +```
  +
  +Or, to install the files system-wide, using:
  +
  +```
  +INSTALL_PREFIX=/usr/local make default install
  +```
  +
  ## Example
  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.
  