Remove references to index.ros.org. (#244)

Signed-off-by: Chris Lalancette <clalancette@gmail.com>

geometry_msgs/msg/TransformStamped.msg

@@ -2,7 +2,7 @@
 # to the coordinate frame child_frame_id at the time of header.stamp
 #
 # This message is mostly used by the
-# <a href="https://index.ros.org/p/tf2/">tf2</a> package.
+# <a href="https://docs.ros.org/en/rolling/p/tf2/">tf2</a> package.
 # See its documentation for more information.
 #
 # The child_frame_id is necessary in addition to the frame_id

visualization_msgs/msg/Marker.msg

@@ -58,7 +58,7 @@ geometry_msgs/Point[] points
 std_msgs/ColorRGBA[] colors
 
 # Texture resource is a special URI that can either reference a texture file in
-# a format acceptable to (resource retriever)[https://index.ros.org/p/resource_retriever/]
+# a format acceptable to (resource retriever)[https://docs.ros.org/en/rolling/p/resource_retriever/]
 # or an embedded texture via a string matching the format:
 #   "embedded://texture_name"
 string texture_resource