Expand ROS Specific Namespace Prefix for Actions

To better secure and segment access control of the different ROS subsystems, specifically to avoid the mapping of ROS2 actions to DDS topics from colliding with those of ROS2 topics and services, actions are to be allocated their own prefix to facilitate simpler policy profile permissions. Additionally, this and helps to prevent crossover of information flow in the case of more general permission prefix expressions.  
Contex: #193 (comment)

articles/140_topic_and_service_name_mapping.md

@@ -210,8 +210,8 @@ In order to differentiate ROS topics easily, all DDS topics created by ROS shall
 For example, a plain topic called `/foo` would translate to a DDS topic `rt/foo`, which is the result of implicitly adding `rt` to the namespace of a ROS topic which is in the root namespace `/` and has a base name `foo`.
 As another example, a topic called `/left/image_raw` would translate to a DDS topic `rt/left/image_raw`, which is the result of implicitly adding `rt` to the namespace of a ROS topic which is in the namespace `/left` and has a base name `image_raw`.
 
-For systems where Services are implemented with topics (like with OpenSplice), a different subsystem character can be used: `rq` for the request topic and `rr` for the response topic.
-On systems where Services are handled explicitly implemented, we consider a separate prefix, e.g. `rs`.
+For systems where Services are implemented with topics (like with OpenSplice), a different subsystem character can be used: `rq` and `raq` for the request topic, `rr` and `rar` for the response topic.
+On systems where Services are handled explicitly implemented, we consider a separate prefix, e.g. `rs` and `ras`.
 
 Here is a non-exhaustive list of prefixes:
 
@@ -222,7 +222,10 @@ Here is a non-exhaustive list of prefixes:
 | ROS Service Response | rr     |
 | ROS Service          | rs     |
 | ROS Parameter        | rp     |
-| ROS Action           | ra     |
+| ROS Action Topics           | rat     |
+| ROS Action Service Request  | raq     |
+| ROS Action Service Response | rar     |
+| ROS Action Service          | ras     |
 
 While all planned prefixes consist of two characters, i.e. `rX`, anything proceeding the first namespace separator, i.e. `/`, can be considered part of the prefix.
 The standard reserves the right to use up to 8 characters for the prefix in case additional prefix space is needed in the future.