WIPWIP update release team template with more info.

.github/ISSUE_TEMPLATE/new_release_team.md

@@ -6,9 +6,15 @@ title: 'Add release team'
 
 * Name of the new release team: <!-- all lower case with words separated by `_`. -->
 * Release repositories to add:
+  <!--
+  If there are any existing release repositories which should have their contents imported into the ros2-gbp organization, list and link to them here.
+  Leave the checkbox _unchecked_. The ros2-gbp administrator will check the box when they have completed the repository import.
+  -->
   * [FIRST_REPOSITORY](SOURCE URL)
+    * [ros/rosdistro source entry](LINK TO SOURCE FIELD IN ROS/ROSDISTRO)
     * [ ] There is an existing release repository which should be imported: <RELEASE REPOSITORY URL>
   * [SECOND REPOSITORY](SOURCE URL)
+    * [ros/rosdistro source entry](LINK TO SOURCE FIELD IN ROS/ROSDISTRO)
     * [ ] There is an existing release repository which should be imported: <RELEASE REPOSITORY URL>
   * ...