AP_DDS: Readme updated with example using altitude_frame

Author: tizianofiorenzani

libraries/AP_DDS/README.md

@@ -299,8 +299,9 @@ The `altitude_frame` specifies the datum for the altitude, among Home, Absolute,
 (use the enumerator specified in the message definition).
 
 ```bash
-ros2 service call /ap/rally_set ardupilot_msgs/srv/RallySet "{rally: {point: {latitude: -35, longitude: 151, altitude: 400}}}"
-requester: making request: ardupilot_msgs.srv.RallySet_Request(rally=ardupilot_msgs.msg.Rally(point=geographic_msgs.msg.GeoPoint(latitude=-35.0, longitude=151.0, altitude=400.0), altitude_frame=0), clear=False)
+ros2 service call /ap/rally_set ardupilot_msgs/srv/RallySet "{rally: {altitude_frame: 1,  point: {latitude: -35, longitude: 151, altitude: 400}}}"
+
+requester: making request: ardupilot_msgs.srv.RallySet_Request(rally=ardupilot_msgs.msg.Rally(point=geographic_msgs.msg.GeoPoint(latitude=-35.0, longitude=151.0, altitude=400.0), altitude_frame=1), clear=False)
 
 response:
 ardupilot_msgs.srv.RallySet_Response(success=True, size=1)
@@ -310,10 +311,11 @@ Get a specific Rally Point (the same service can be used to request the size of
 
 ```bash
 ros2 service call /ap/rally_get ardupilot_msgs/srv/RallyGet "index: 0"
+
 requester: making request: ardupilot_msgs.srv.RallyGet_Request(index=0)
 
 response:
-ardupilot_msgs.srv.RallyGet_Response(success=True, size=1, rally=ardupilot_msgs.msg.Rally(point=geographic_msgs.msg.GeoPoint(latitude=-35.0, longitude=151.0, altitude=400.0), altitude_frame=0))
+ardupilot_msgs.srv.RallyGet_Response(success=True, size=1, rally=ardupilot_msgs.msg.Rally(point=geographic_msgs.msg.GeoPoint(latitude=-35.0, longitude=151.0, altitude=400.0), altitude_frame=1))
 ```
 
 ## Commanding using ROS 2 Topics