integrations: Add documentation for Front.

zerver/webhooks/front/doc.md

@@ -0,0 +1,37 @@
+Front lets you manage all of your communication channels in one place,
+and helps your team collaborate around every message. Follow these steps
+to recieve Front notifications without leaving Zulip!
+
+{!create-stream.md!}
+
+{!create-bot-construct-url.md!}
+
+Then, log into your Front account, and do the following:
+
+1. Go to the **Settings** of your organization.
+   ![](/static/images/integrations/front/001.png)
+
+2. Enable webhook notifications.
+   ![](/static/images/integrations/front/002.png)
+   ![](/static/images/integrations/front/003.png)
+
+3. Pick the types of events for which you want to receive notifications,
+and set the URL you construsted for the Front bot as a target webhook.
+   ![](/static/images/integrations/front/004.png)
+   ![](/static/images/integrations/front/005.png)
+
+Finally, go to the **Settings** of your Zulip organization, and add a new
+filter on the **Filter settings** page.
+
+**Pattern**: `cnv_(?P<id>[0-9a-z]+)`.
+**URL format string**: `https://app.frontapp.com/open/cnv_%(id)s`.
+
+![](/static/images/integrations/front/006.png)
+
+This step is necessary to set a link to a Front conversation as a name of
+the corresponding topic in Zulip.
+
+{!congrats.md!}
+
+![](/static/images/integrations/front/007.png)
+![](/static/images/integrations/front/008.png)