Added a section "Developing your webhooks"

This will be quite helpful to fellow developers. I used this technique for faster integrations with Gitlab webhooks during my local development.

doc/user/project/integrations/webhooks.md

@@ -274,6 +274,33 @@ Webhook requests to your endpoint include the following headers:
 | `X-Gitlab-Event` | Name of the webhook type. Corresponds to [event types](webhook_events.md) but in the format `"<EVENT> Hook"`. | `"Push Hook"` |
 | `X-Gitlab-Event-UUID` | Unique ID per webhook that is not recursive. A hook is recursive if triggered by an earlier webhook that hit the GitLab instance. Recursive webhooks have the same value for this header. | `"13792a34-cac6-4fda-95a8-c58e00a3954e"` |
 
+## Develop webhooks
+
+If you don't have an existing HTTPS endpoint or URL for your webhook setup, you must deploy one on a server. This HTTPS endpoint is used in configuration. To develop against GitLab webhooks and capture the payloads, you can use:
+
+- [Public webhook inspection and testing tools](#public-webhook-inspection-and-testing-tools)
+- [The GitLab Development Kit (GDK)](#gitlab-development-kit-gdk)
+- [Recently triggered webhook payloads in GitLab settings](#recently-triggered-webhook-payloads-in-gitlab-settings)
+
+### Public webhook inspection and testing tools
+
+You can use public tools to inspect and test webhook payloads. These tools act as catch-all endpoints for HTTP requests and respond with a `200 OK` HTTP status code. You can use these payloads to develop your webhook services.
+
+You should exercise caution when using these tools as you might be sending sensitive data to external tools. You should use test tokens with these tools and rotate any secrets inadvertently sent to a third party.
+
+These public tools include:
+
+- [Beeceptor](https://beeceptor.com) to create a temporary HTTPS endpoint and inspect incoming payloads
+- [Webhook.site](https://webhook.site) to review incoming payloads
+
+### GitLab Development Kit (GDK)
+
+For a safer development environment, you can use the [GitLab Development Kit (GDK)](https://gitlab.com/gitlab-org/gitlab-development-kit) to develop against GitLab webhooks locally. With the GDK, you can send webhooks from your local GitLab instance to a webhook receiver running locally on your machine. To use this approach, you must install and configure the GDK.
+
+### Recently triggered webhook payloads in GitLab settings
+
+You can [review recently triggered webhook payloads](#troubleshooting) in GitLab settings. For each webhook event, a detail page exists with information about the data GitLab sends and receives from the webhook endpoint.
+
 ## Troubleshooting
 
 > **Recent events** for group webhooks [introduced](https://gitlab.com/gitlab-org/gitlab/-/issues/325642) in GitLab 15.3.