integration-docs: Update Trello for new doc format.

Part of zulip#29592.

zerver/webhooks/trello/doc.md

@@ -1,67 +1,83 @@
-!!! tip ""
-
-    Note that [Zapier][1] is usually a simpler way to
-    integrate Trello with Zulip.
+# Zulip Trello integration
 
 Get Zulip notifications from your Trello boards!
 
-[1]: ./zapier
+!!! tip ""
+
+    [Zapier](./zapier) is usually a simpler way to integrate Trello
+    with Zulip.
+
+{start_tabs}
 
 1. {!create-channel.md!}
 
 1. {!create-an-incoming-webhook.md!}
 
-1. {!generate-integration-url.md!}
+1. {!generate-webhook-url-basic.md!}
 
-1. **Log in to Trello**, and collect the following three items:
+1. **Log in to Trello**, and collect the following:
 
     * **Board ID**: Go to your Trello board. The URL should look like
       `https://trello.com/b/<BOARD_ID>/<BOARD_NAME>`. Note down the
       `<BOARD_ID>`.
 
-    * **API Key**: Go to <https://trello.com/1/appkey/generate>. Note down the
-      key listed under **Developer API Keys**.
+    * **API Key**: Go to <https://trello.com/1/appkey/generate>. Note down
+      the key listed under **Developer API Keys**.
 
-    * **User Token**: Go to <https://trello.com/1/appkey/generate>. Under
-      **Developer API Keys**, click on the **Token** link. Click on **Allow**.
-      Note down the token generated.
+    * **User Token**: Under **Developer API Keys**, click on the **Token**
+      link, and click **Allow**. Note down the token generated.
 
-    You're now going to need to run a Trello configuration script from a
+1.  You're now going to need to run a Trello configuration script from a
     computer (any computer) connected to the internet. It won't make any
     changes to the computer.
 
-1. Make sure you have a working copy of Python. If you're running
+    Make sure you have a working copy of Python. If you're running
     macOS or Linux, you very likely already do. If you're running
     Windows you may or may not.  If you don't have Python, follow the
-    installation instructions
-    [here](https://realpython.com/installing-python/). Note that you
-    do not need the latest version of Python; anything 2.7 or higher
-    will do.
+    installation instructions [here][1].
 
-1. Download [zulip-trello.py][2]. `Ctrl+s` or `Cmd+s` on that page should
-   work in most browsers.
+    !!! tip ""
 
-1. Run the `zulip-trello` script in a terminal, after replacing the all caps
-   arguments with the values collected above.
+        You do not need the latest version of Python; anything 2.7 or
+        higher will do.
+
+1. Download [zulip-trello.py][2].
+
+    !!! tip ""
+
+        `Ctrl+s` or `Cmd+s` on that page should work in most browsers.
+
+1. Run the `zulip-trello` script in a terminal, after replacing the all
+   caps arguments with the values collected above and the generated URL
+   above.
 
     ```
     python zulip_trello.py --trello-board-name  TRELLO_BOARD_NAME \
                            --trello-board-id  TRELLO_BOARD_ID \
                            --trello-api-key  TRELLO_API_KEY \
                            --trello-token  TRELLO_TOKEN \
-                           --zulip-webhook-url  "ZULIP_WEBHOOK_URL"
+                           --zulip-webhook-url  "GENERATED_WEBHOOK_URL"
     ```
 
-    **Note**: Make sure that you wrap the webhook URL in quotes
-    when supplying it on the command-line, as shown above.
+    !!! warn ""
+
+        **Note**: Make sure that you wrap the webhook URL generated above
+        in quotes when supplying it on the command-line, as shown above.
 
     The `zulip_trello.py` script only needs to be run once, and can be run
     on any computer with python.
 
 1. You can delete `zulip_trello.py` from your computer if you'd like.
 
-[2]: https://raw.githubusercontent.com/zulip/python-zulip-api/main/zulip/integrations/trello/zulip_trello.py
+{end_tabs}
 
 {!congrats.md!}
 
 ![](/static/images/integrations/trello/001.png)
+
+### Related documentation
+
+{!webhooks-url-specification.md!}
+
+[1]: https://realpython.com/installing-python/
+[2]: https://raw.githubusercontent.com/zulip/python-zulip-api/main/zulip/integrations/trello/zulip_trello.py