Add more docs for severity quick actions

doc/operations/incident_management/incidents.md

@@ -238,6 +238,8 @@ Associate an incident to a milestone by selecting **Edit** next to the milestone
 See [Incident List](#incident-list) for a full description of the severity levels available.
 Select **Edit** in the right-hand side bar to change the severity of an incident.
 
+You can also change the severity using the [`/severity` quick action](../../user/project/quick_actions.md).
+
 ### Add a to-do item
 
 Add a to-do for incidents that you want to track in your to-do list. Click the

doc/user/project/quick_actions.md

@@ -94,7 +94,7 @@ threads. Some quick actions might not be available to all subscription tiers.
 | `/remove_time_spent`                  | **{check-circle}** Yes | **{check-circle}** Yes | **{dotted-circle}** No | Remove time spent. |
 | `/remove_zoom`                        | **{check-circle}** Yes | **{dotted-circle}** No | **{dotted-circle}** No | Remove Zoom meeting from this issue ([introduced in GitLab 12.4](https://gitlab.com/gitlab-org/gitlab/-/merge_requests/16609)). |
 | `/reopen`                             | **{check-circle}** Yes | **{check-circle}** Yes | **{check-circle}** Yes | Reopen. |
-| `/severity`                           | **{check-circle}** Yes | **{check-circle}** No  | **{check-circle}** No  | Set the severity. ([introduced in GitLab 14.2](https://gitlab.com/gitlab-org/gitlab/-/issues/334045)) |
+| `/severity <severity>`                | **{check-circle}** Yes | **{check-circle}** No  | **{check-circle}** No  | Set the severity. Options for `<severity>` are `S1` ... `S4`, `critical`, `high`, `medium`, `low`, `unknown`. [Introduced in GitLab 14.2](https://gitlab.com/gitlab-org/gitlab/-/issues/334045). |
 | `/shrug <comment>`                    | **{check-circle}** Yes | **{check-circle}** Yes | **{check-circle}** Yes | Append the comment with `¯\＿(ツ)＿/¯`. |
 | `/spend <time> [<date>]` | **{check-circle}** Yes | **{check-circle}** Yes | **{dotted-circle}** No | Add or subtract spent time. Optionally, specify the date that time was spent on. For example, `/spend 1mo 2w 3d 4h 5m 2018-08-26` or `/spend -1h 30m`. Learn more about [time tracking](time_tracking.md). |
 | `/submit_review`                      | **{dotted-circle}** No | **{check-circle}** Yes | **{dotted-circle}** No | Submit a pending review ([introduced in GitLab 12.7](https://gitlab.com/gitlab-org/gitlab/-/issues/8041)). |