integration-docs: Update Git for new doc format.

Part of zulip#29592.

templates/zerver/integrations/git.md

@@ -1,5 +1,9 @@
+# Zulip Git integration
+
 Get Zulip notifications for your Git repositories!
 
+{start_tabs}
+
 1. {!create-an-incoming-webhook.md!}
 
 1. {!download-python-bindings.md!}
@@ -8,12 +12,16 @@ Get Zulip notifications for your Git repositories!
 
 1. {!change-zulip-config-file.md!}
 
-    You may also need to change the value of `STREAM_NAME`.
+    ```
+    STREAM_NAME = "<Name of your channel>"
+    ```
 
-    You can specify the branches that will be used for notifications by modifying
-    the `commit_notice_destination` function. By default,
-    pushes to the `main`, `master`, and `test-post-receive` branches will result in a
-    notification.
+    !!! tip ""
+
+        Customize notification branches by editing the
+        `commit_notice_destination` function. By default,
+        pushes to the `main`, `master`, and `test-post-receive` branches will
+        result in a notification.
 
 1. Symlink `/usr/local/share/zulip/integrations/git/zulip_git_config.py`
    to the `.git/hooks` directory of your Git repository.
@@ -23,8 +31,10 @@ Get Zulip notifications for your Git repositories!
 
 !!! tip ""
 
-    You can test the plugin without changing your `main` branch by
-    pushing to the `test-post-receive` branch.
+    Use the `test-post-receive` branch to safely test the plugin without
+    modifying your main branch.
+
+{end_tabs}
 
 {!congrats.md!}