Correct the description of sendGoal function

Fix #689

Author: Minggang Wang

lib/action/client.js

@@ -188,10 +188,10 @@ class ActionClient extends Entity {
   }
 
   /**
-   * Send a goal and asynchronously get the result.
+   * Send a goal and wait for the goal ACK asynchronously.
    *
-   * The result of the returned Promise is set to a ClientGoalHandle when receipt of the goal
-   * is acknowledged by an action server.
+   * Return a Promise object that is resolved with a ClientGoalHandle when receipt of the goal
+   * is acknowledged by an action server, see client state transition https://index.ros.org/doc/ros2/Tutorials/Understanding-ROS2-Actions/
    *
    * @param {object} goal - The goal request.
    * @param {function} feedbackCallback - Callback function for feedback associated with the goal.
@@ -259,7 +259,7 @@ class ActionClient extends Entity {
       if (timeout !== undefined && timeout >= -1) {
         waitMs = Math.min(waitMs, deadline - Date.now());
       }
-      await new Promise(resolve => setTimeout(resolve, waitMs));
+      await new Promise((resolve) => setTimeout(resolve, waitMs));
       serviceAvailable = this.isActionServerAvailable();
     }
     return serviceAvailable;
@@ -305,7 +305,10 @@ class ActionClient extends Entity {
   }
 
   /**
-   * Request the result for an active goal asynchronously.
+   * Get the result of an active goal asynchronously.
+   *
+   * Return a Promise object that is resolved with result, see client state transition https://index.ros.org/doc/ros2/Tutorials/Understanding-ROS2-Actions/
+   *
    * @ignore
    * @param {ClientGoalHandle} goalHandle - Handle to the goal to cancel.
    * @returns {Promise} - A Promise that resolves when the get result request has been processed.

types/action_client.d.ts

@@ -99,10 +99,10 @@ declare module 'rclnodejs' {
     );
 
     /**
-     * Send a goal and asynchronously get the result.
+     * Send a goal and wait for the goal ACK asynchronously.
      *
-     * The result of the returned Promise is set to a ClientGoalHandle when receipt of the goal
-     * is acknowledged by an action server.
+     * Return a Promise object that is resolved with a ClientGoalHandle when receipt of the goal
+     * is acknowledged by an action server, see client state transition https://index.ros.org/doc/ros2/Tutorials/Understanding-ROS2-Actions/
      *
      * @param goal - The goal request.
      * @param feedbackCallback - Callback function for feedback associated with the goal.