description: use standard comments for base and tool0 frames.

Aligned with other ROS-Industrial robot support packages.

ur_description/urdf/ur_macro.xacro

@@ -297,7 +297,7 @@
       <dynamics damping="0" friction="0"/>
     </joint>
 
-    <!-- ROS base_link to UR 'Base' Coordinates transform -->
+    <!-- ROS-Industrial 'base' frame: base_link to UR 'Base' Coordinates transform -->
     <link name="${prefix}base"/>
     <joint name="${prefix}base_link-base_fixed_joint" type="fixed">
       <!-- NOTE: this rotation is only needed as long as base_link itself is
@@ -317,7 +317,7 @@
       <origin xyz="0 0 0" rpy="0 ${-pi/2.0} ${-pi/2.0}" />
     </joint>
 
-    <!-- Frame coincident with all-zeros TCP on UR controller -->
+    <!-- ROS-Industrial 'tool0' frame: all-zeros tool frame -->
     <link name="${prefix}tool0"/>
     <joint name="${prefix}flange-tool0" type="fixed">
       <!-- default toolframe: X+ left, Y+ up, Z+ front -->