improve docs

Author: viblo

pymunk/shape_filter.py

@@ -122,12 +122,14 @@ def rejects_collision(self, other: "ShapeFilter") -> bool:
 
             >>> ShapeFilter().rejects_collision(ShapeFilter())
             False
-            >>> ShapeFilter(group=1).rejects_collision(ShapeFilter())
+            >>> ShapeFilter(group=1).rejects_collision(ShapeFilter(group=2))
             False
             >>> ShapeFilter(group=1).rejects_collision(ShapeFilter(group=1))
             True
 
 
+        Categories and Masks::
+
             >>> default = ShapeFilter()
             >>> default.rejects_collision(default)
             False