Add description about normalized thrust

This commit was added to address the review comments

message_definitions/v1.0/common.xml

@@ -4967,7 +4967,7 @@
       <field type="float" name="body_yaw_rate" units="rad/s">Body yaw rate</field>
       <field type="float" name="thrust">Collective thrust, normalized to 0 .. 1 (-1 .. 1 for vehicles capable of reverse trust)</field>
       <extensions/>
-      <field type="float[3]" name="thrust_body">3D thrust setpoint in the body NED frame</field>
+      <field type="float[3]" name="thrust_body">3D thrust setpoint in the body NED frame, normalized to -1 .. 1</field>
     </message>
     <message id="83" name="ATTITUDE_TARGET">
       <description>Reports the current commanded attitude of the vehicle as specified by the autopilot. This should match the commands sent in a SET_ATTITUDE_TARGET message if the vehicle is being controlled this way.</description>