docs: add pull over description for fail-safe doc (#461)

* add pull over description for fail-safe doc

Signed-off-by: asana17 <akihiro.sakurai@tier4.jp>

* style(pre-commit): autofix

* update mrm behavior image for fail-safe doc

Signed-off-by: asana17 <akihiro.sakurai@tier4.jp>

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Signed-off-by: asana17 <akihiro.sakurai@tier4.jp>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

Author: asana17

docs/design/autoware-interfaces/ad-api/features/fail-safe.md

@@ -41,3 +41,4 @@ This is service dependent. Autoware supports the following transitions by defaul
 | NONE             | MRM is not operating or is operating but no special behavior is required. |
 | COMFORTABLE_STOP | The vehicle will stop quickly with a comfortable deceleration.            |
 | EMERGENCY_STOP   | The vehicle will stop immediately with as much deceleration as possible.  |
+| PULL_OVER        | The vehicle will stop after moving to the side of the road.               |