[v11.0/forgejo] fix(api): document is_system_webhook field (#7786)

**Backport:** https://codeberg.org/forgejo/forgejo/pulls/7784

- Document that `is_system_webhook` field is accepted for the `POST /admin/hooks` endpoint.

Co-authored-by: Gusted <postmaster@gusted.xyz>
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/7786
Co-authored-by: forgejo-backport-action <forgejo-backport-action@noreply.codeberg.org>
Co-committed-by: forgejo-backport-action <forgejo-backport-action@noreply.codeberg.org>

modules/structs/hook.go

@@ -54,6 +54,7 @@ type CreateHookOption struct {
 	AuthorizationHeader string                 `json:"authorization_header"`
 	// default: false
 	Active          bool `json:"active"`
+	IsSystemWebhook bool `json:"is_system_webhook"`
 }
 
 // EditHookOption options when modify one hook

templates/swagger/v1_json.tmpl

@@ -22178,6 +22178,10 @@
           },
           "x-go-name": "Events"
         },
+        "is_system_webhook": {
+          "type": "boolean",
+          "x-go-name": "IsSystemWebhook"
+        },
         "type": {
           "type": "string",
           "enum": [