fix wrong units & improve explanation for subTree migration (ros-navigation#867)

* fix wrong units

Signed-off-by: Adi Vardi <adi.vardi@enway.ai>

* Clearer explanation

Signed-off-by: Adi Vardi <adi.vardi@enway.ai>

* rm some line breaks

---------

Signed-off-by: Adi Vardi <adi.vardi@enway.ai>
Signed-off-by: Jaerak Son <sjr9017@naver.com>

Author: adivardi

configuration/packages/configuring-bt-navigator.rst

@@ -110,7 +110,7 @@ Parameters
   ==== =======
 
   Description
-    Default timeout value (in milliseconds) while a BT action node is waiting for acknowledgement from an action server.
+    Default timeout value (in milliseconds) for a BT action node to wait for acknowledgement from an action server.
     This value will be overwritten for a BT node if the input port "server_timeout" is provided.
 
 :default_cancel_timeout:
@@ -122,7 +122,7 @@ Parameters
   ==== =======
 
   Description
-    Default timeout (in seconds) for BT action node cancellation requests during node halt.
+    Default timeout (in milliseconds) for BT action node cancellation requests during node halt.
     This value will be overwritten for a BT node if the input port "cancel_timeout" is provided.
 
 :wait_for_service_timeout:
@@ -134,7 +134,7 @@ Parameters
   ==== =======
 
   Description
-    Default timeout value (in milliseconds) while Action or Service BT nodes will waiting for acknowledgement from an service or action server on BT initialization (e.g. ``wait_for_action_server(timeout)``).
+    Default timeout value (in milliseconds) for an Action or Service BT nodes to wait for acknowledgement from an service or action server on BT initialization (e.g. ``wait_for_action_server(timeout)``).
     This value will be overwritten for a BT node if the input port "wait_for_service_timeout" is provided.
 
 :introspection_mode:
@@ -257,7 +257,7 @@ Parameters
   ============== ==================================================
 
   Description
-    List of directories that hosts behavior trees XML files. It is needed to register all behavior trees as well as subtrees.
+    List of directories that hosts behavior trees XML files. Used to register all behavior trees and subtrees.
 
 NavigateToPose Parameters
 *************************

migration/Kilted.rst

@@ -361,10 +361,12 @@ See also :ref:`configuring_bt_navigator`
 Add BehaviorTree SubTrees Support
 ---------------------------------
 
-The BehaviorTree engine now supports SubTrees in different files within directory(s) set through ``bt_search_directories`` parameter. This allows you to modularize your behavior trees into smaller components that can be reused across different trees.
-The interface now supports passing the behavior tree file or ID as input to the `loadBehaviorTree` method of the BT action server.
-Each behavior tree is now strictly required to have its own unique ID, therefore the need to replace `MainTre` to a unique ID. For example, in `navigate_through_poses_w_replanning_and_recovery.xml
-` `MainTree` can be replaced with `NavigateThroughPosesWReplanningAndRecovery`.
+The BehaviorTree engine now supports loading SubTrees from multiple files.
+This allows you to modularize your behavior trees into smaller components that can be reused across different trees.
+The .xml files should be located within directory(s) set through the ``bt_search_directories`` parameter.
+
+The interface also supports requesting the desired behavior tree as a filepath or as an ID.
+To use the ID or multiple SubTrees features, each behavior tree is required to have its own unique ID - replace `MainTree` with a unique ID.
 
 Option to have custom window size and poly order in Savitsky-Golay Smoother
 ---------------------------------------------------------------------------