Merge branch 'nrosandich-streaming-audit-event-json-type' into 'master'

Add streaming content type header info to docs

See merge request !124008



Merged-by: Nathan Rosandich <nrosandich@gitlab.com>

doc/administration/audit_event_streaming.md

@@ -512,6 +512,12 @@ To list streaming destinations for an instance and see the verification tokens:
 1. On the main area, select the **Streams**.
 1. View the verification token on the right side of each item.
 
+## Content type header
+
+Each streaming destination by default uses the `content-type` header of `application/x-www-form-urlencoded`.
+
+To override this default value use the custom headers to add a different `content-type` eg `application/json`. This can be done through either the [GitLab UI](#use-the-gitlab-ui-2) or using the [API](#use-the-api-2). This can be done at both the top-level group and instance streaming audit event destinations.
+
 ## Event type filters
 
 > - Event type filters API [introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/344845) in GitLab 15.7.