Add smoothing_angle_threshold parameter description for Route Server (#868)

* Add smoothing_angle_threshold parameter description for Route Server

Signed-off-by: RayOwwen <rayowwen@gmail.com>

* Apply suggestion from @SteveMacenski

Signed-off-by: Steve Macenski <stevenmacenski@gmail.com>

---------

Signed-off-by: RayOwwen <rayowwen@gmail.com>
Signed-off-by: Steve Macenski <stevenmacenski@gmail.com>
Co-authored-by: Steve Macenski <stevenmacenski@gmail.com>

Author: RayOwwen

configuration/packages/configuring-route-server.rst

@@ -113,6 +113,17 @@ Server Parameters
   Description
     Radius to fit to corners formed by edges if corner smoothing is enabled
 
+:smoothing_angle_threshold:
+
+  ============== ========
+  Type           Default
+  -------------- --------
+  double          2.9
+  ============== ========
+
+  Description
+    Angle threshold (rad). If angle > threshold, no smoothing is applied. This prevents unnecessary smoothing of largely straight segments caused by small differences or annotation error. 2.9 rad is 166 deg, meaning it will not smooth for segments that are within 14 deg of straight anti-parallel.
+
 :costmap_topic:
 
   ============== ============================