Clarify DO_REPOSITION vs NAV_WAYPOINT (#2002)

* Clarify DO_REPOSITION vs NAV_WAYPOINT

* Apply suggestions from code review

message_definitions/v1.0/common.xml

@@ -1082,7 +1082,7 @@
     <enum name="MAV_CMD">
       <description>Commands to be executed by the MAV. They can be executed on user request, or as part of a mission script. If the action is used in a mission, the parameter mapping to the waypoint/mission message is as follows: Param 1, Param 2, Param 3, Param 4, X: Param 5, Y:Param 6, Z:Param 7. This command list is similar what ARINC 424 is for commercial aircraft: A data format how to interpret waypoint/mission data. NaN and INT32_MAX may be used in float/integer params (respectively) to indicate optional/default values (e.g. to use the component's current yaw or latitude rather than a specific value). See https://mavlink.io/en/guide/xml_schema.html#MAV_CMD for information about the structure of the MAV_CMD entries</description>
       <entry value="16" name="MAV_CMD_NAV_WAYPOINT" hasLocation="true" isDestination="true">
-        <description>Navigate to waypoint.</description>
+        <description>Navigate to waypoint. This is intended for use in missions (for guided commands outside of missions use MAV_CMD_DO_REPOSITION).</description>
         <param index="1" label="Hold" units="s" minValue="0">Hold time. (ignored by fixed wing, time to stay at waypoint for rotary wing)</param>
         <param index="2" label="Accept Radius" units="m" minValue="0">Acceptance radius (if the sphere with this radius is hit, the waypoint counts as reached)</param>
         <param index="3" label="Pass Radius" units="m">0 to pass through the WP, if &gt; 0 radius to pass by WP. Positive value for clockwise orbit, negative value for counter-clockwise orbit. Allows trajectory control.</param>
@@ -1544,7 +1544,7 @@
         <param index="7">Empty</param>
       </entry>
       <entry value="192" name="MAV_CMD_DO_REPOSITION" hasLocation="true" isDestination="true">
-        <description>Reposition the vehicle to a specific WGS84 global position.</description>
+        <description>Reposition the vehicle to a specific WGS84 global position. This command is intended for guided commands (for missions use MAV_CMD_NAV_WAYPOINT instead).</description>
         <param index="1" label="Speed" units="m/s" minValue="-1">Ground speed, less than 0 (-1) for default</param>
         <param index="2" label="Bitmask" enum="MAV_DO_REPOSITION_FLAGS">Bitmask of option flags.</param>
         <param index="3" label="Radius" units="m">Loiter radius for planes. Positive values only, direction is controlled by Yaw value. A value of zero or NaN is ignored. </param>