Some docs tweaks (#2190)

* add v4 tag to playwright extension

* add self-hosting architecture section

* add v4-beta tag warning

docs/config/extensions/playwright.mdx

@@ -2,8 +2,13 @@
 title: "Playwright"
 sidebarTitle: "playwright"
 description: "Use the playwright build extension to use Playwright with Trigger.dev"
+tag: "v4"
 ---
 
+import UpgradeToV4Note from "/snippets/upgrade-to-v4-note.mdx";
+
+<UpgradeToV4Note />
+
 If you are using [Playwright](https://playwright.dev/), you should use the Playwright build extension.
 
 - Automatically installs Playwright and required browser dependencies

docs/self-hosting/docker.mdx

@@ -105,6 +105,10 @@ docker compose logs -f webapp
 npx trigger.dev@v4-beta init -p <project-ref> -a http://localhost:8030
 ```
 
+<Warning>
+The commands displayed in the webapp are incorrect while v4 is in beta. You should always use the `v4-beta` tag and not `latest`.
+</Warning>
+
 {/* 7. Bonus: Add traefik as a reverse proxy
 
 ```bash

docs/self-hosting/overview.mdx

@@ -19,7 +19,14 @@ Because we don't manage self-hosted instances, we cannot guarantee how Trigger.d
 
 For more details, carry on reading and follow our guides for instructions on setting up a self-hosted Trigger.dev instance. If you prefer a managed experience, you can [sign up](https://cloud.trigger.dev/login) for our Cloud offering instead - we have a generous [free tier](https://trigger.dev/pricing) for you to try it out.
 
-{/* TODO: Architecture section with updated diagram */}
+## Architecture
+
+The self-hosted version is a set of containers running on your own infrastructure. It's split into two parts that can be scaled independently:
+
+- **Webapp**: includes the dashboard and other services like Redis and Postgres.
+- **Worker**: includes the supervisor and the runners that execute your tasks.
+
+![Self-hosting architecture](./architecture.png)
 
 ## Feature comparison