updated collision sensor documentation

Docs/python_api.md

@@ -596,7 +596,7 @@ Sets the maxixum time a network call is allowed before blocking it and raising a
 
 ## carla.CollisionEvent<a name="carla.CollisionEvent"></a>
 <small style="display:block;margin-top:-20px;">Inherited from _[carla.SensorData](#carla.SensorData)_</small></br>
-Class that defines a collision data for <b>sensor.other.collision</b>. The sensor creates one of this for every collision detected which may be many for one simulation step. Learn more about this [here](ref_sensors.md#collision-detector).  
+Class that defines a collision data for <b>sensor.other.collision</b>. The sensor creates one of these for every collision detected. Each collision sensor produces one collision event per collision per frame. Multiple collision events may be produced in a single frame by collisions with multiple other actors. Learn more about this [here](ref_sensors.md#collision-detector).  
 
 ### Instance Variables
 - <a name="carla.CollisionEvent.actor"></a>**<font color="#f8805a">actor</font>** (_[carla.Actor](#carla.Actor)_)  

Docs/ref_sensors.md

@@ -25,8 +25,7 @@
 * __Blueprint:__ sensor.other.collision
 * __Output:__ [carla.CollisionEvent](python_api.md#carla.CollisionEvent) per collision.
 
-This sensor registers an event each time its parent actor collisions against something in the world. Several collisions may be detected during a single simulation step.
-To ensure that collisions with any kind of object are detected, the server creates "fake" actors for elements such as buildings or bushes so the semantic tag can be retrieved to identify it.
+This sensor registers an event each time its parent actor collides against something in the world. Each collision sensor produces one collision event per collision per frame. Multiple collision events may be produced in a single frame by collisions with multiple other actors. To ensure that collisions with any kind of object are detected, the server creates "fake" actors for elements such as buildings or bushes so the semantic tag can be retrieved to identify it.
 
 Collision detectors do not have any configurable attribute.
 

PythonAPI/docs/sensor_data.yml

@@ -379,7 +379,7 @@
     parent: carla.SensorData
     # - DESCRIPTION ------------------------
     doc: >
-      Class that defines a collision data for <b>sensor.other.collision</b>. The sensor creates one of this for every collision detected which may be many for one simulation step. Learn more about this [here](ref_sensors.md#collision-detector).
+      Class that defines a collision data for <b>sensor.other.collision</b>. The sensor creates one of these for every collision detected. Each collision sensor produces one collision event per collision per frame. Multiple collision events may be produced in a single frame by collisions with multiple other actors. Learn more about this [here](ref_sensors.md#collision-detector).
     # - PROPERTIES -------------------------
     instance_variables:
     - var_name: actor