docs(behavior_velocity): organize traffic light color action (#7049)

Signed-off-by: Mamoru Sobue <[email protected]>

planning/behavior_velocity_planner/README.md

@@ -56,3 +56,15 @@ So for example, in order to stop at a stop line with the vehicles' front on the
 | `max_accel`            | double               | (to be a global parameter) max acceleration of the vehicle                          |
 | `system_delay`         | double               | (to be a global parameter) delay time until output control command                  |
 | `delay_response_time`  | double               | (to be a global parameter) delay time of the vehicle's response to control commands |
+
+## Traffic Light Handling in sim/real
+
+The handling of traffic light information varies depending on the usage. In the below table, the traffic signal topic element for the corresponding lane is denoted as `info`, and if `info` is not available, it is denoted as `null`.
+
+| module \\ case                                                                                             | `info` is `null`         | `info` is not `null`                                                                                                                                                                                                                                                                 |
+| :--------------------------------------------------------------------------------------------------------- | ------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
+| intersection_occlusion(`is_simulation = *`) <ul> <li>`info` is the latest non-`null` information</li></ul> | GO(occlusion is ignored) | intersection_occlusion uses the latest non UNKNOWN observation in the queue up to present.<ul><li>If `info` is `GREEN or UNKNOWN`, occlusion is cared</li><li>If `info` is `RED or YELLOW`, occlusion is ignored(GO) </li> <li> NOTE: Currently timeout is not considered</li> </ul> |
+| traffic_light(sim, `is_simulation = true`) <ul> <li>`info` is current information</li></ul>                | GO                       | traffic_light uses the perceived traffic light information at present directly. <ul><li>If `info` is timeout, STOP whatever the color is</li> <li>If `info` is not timeout, then act according to the color. If `info` is `UNKNOWN`, STOP</li></ul> {: rowspan=2}                    |
+| traffic_light(real, `is_simulation = false`) <ul> <li>`info` is current information</li></ul>              | STOP                     | &#8288 {: style="padding:0"}                                                                                                                                                                                                                                                         |
+| crosswalk with Traffic Light(`is_simulation = *`) <ul> <li>`info` is current information</li></ul>         | default                  | <ul> <li>If `disable_yield_for_new_stopped_object` is true, each sub scene_module ignore newly detected pedestrians after module instantiation.</li> <li>If `ignore_with_traffic_light` is true, occlusion detection is skipped.</li></ul>                                           |
+| map_based_prediction(`is_simulation = *`) <ul> <li>`info` is current information</li></ul>                 | default                  | If a pedestrian traffic light is<ul> <li>RED, surrouding pedestrians are not predicted.</li> <li>GREEN, stopped pedestrians are not predicted.</li></ul>                                                                                                                             |