Add full deployment guide on deploying to Fly.io (withastro#7812)

Co-authored-by: Sarah Rainsberger <[email protected]>

src/content/docs/en/guides/deploy/flyio.mdx

@@ -8,6 +8,36 @@ stub: true
 
 You can deploy your Astro project to [Fly.io](https://fly.io/), a platform for running full stack apps and databases close to your users.
 
+## Project Configuration
+
+Your Astro project can be deployed to Fly.io as a static site, or as a server-side rendered site (SSR).
+
+### Static Site
+
+Your Astro project is a static site by default. You don’t need any extra configuration to deploy a static Astro site to Fly.io.
+
+### Adapter for SSR
+
+To enable on-demand rendering in your Astro project and deploy on Fly.io, add [the Node.js adapter](/en/guides/integrations-guide/node/).
+
+## How to deploy
+
+1. [Sign up for Fly.io](https://fly.io/docs/getting-started/log-in-to-fly/#first-time-or-no-fly-account-sign-up-for-fly) if you haven't already.
+2. [Install `flyctl`](https://fly.io/docs/hands-on/install-flyctl/), your Fly.io app command center.
+3. Run the following command in your terminal.
+
+    ```bash
+    fly launch
+    ```
+
+	`flyctl` will automatically detect Astro, configure the correct settings, build your image, and deploy it to the Fly.io platform. 
+
+## Generating your Astro Dockerfile
+
+If you don't already have a Dockerfile, `fly launch` will generate one for you, as well as prepare a `fly.toml` file. For `server` or `hybrid` projects, this Dockerfile will include the appropriate start command and environment variables.
+
+You can instead create your own Dockerfile using [Dockerfile generator](https://www.npmjs.com/package/@flydotio/dockerfile) and then run using the command `npx dockerfile` for Node applications or `bunx dockerfile` for Bun applications.
+
 ## Official Resources
 
 - Check out [the official Fly.io docs](https://fly.io/docs/js/frameworks/astro/)