Update default value / remove reference to global param

Signed-off-by: Luca Della Vedova <[email protected]>

configuration/packages/costmap-plugins/static.rst

@@ -67,11 +67,11 @@ This implements a costmap layer taking in a map from either SLAM or ``map_server
   ====== =======
   Type   Default
   ------ -------
-  string ""
+  string "map"
   ====== =======
 
   Description
-    Map topic to subscribe to. If left empty the map topic will default to the global `map_topic` parameter in `costmap_2d_ros`.
+    Map topic to subscribe to.
 
   Relative topics will be relative to the node's parent namespace.
   For example, if you specify `map_topic: map` in the `static_layer` of a `global_costmap` and you launch your bringup with a `tb4` namespace: