Write a README

I adapted this from the one I wrote last night for the
`openneo-analytics` repo!

README.md

@@ -1,3 +1,43 @@
 # OpenNeo Code
 
-TODO: Write this! <3
+This is the deployment code we use to set up and manage code.openneo.net,
+a self-hosted copy of [Forgejo][fj]! It's a very GitHub-like service, but we
+control the data. (Microsoft's recent approach to AI has me feeling real
+anxious about continuing to develop on there!)
+
+We like to use Ansible playbooks to keep track of how we set up our servers,
+here's how we've structured them! (We don't use very fancy Ansible features:
+these are all very basic commands, captured in script form for convenience!)
+
+- `setup-users.yml`: Sets up the user accounts for the system, with their SSH
+  keys for login.
+- `setup-security.yml`: Sets up firewall rules and automatic system updates.
+  (This is a standard playbook I use for all my servers!)
+- `setup-forgejo.yml`: Sets up the Forgejo server itself, as a `systemd`
+  service running Forgejo's official Linux binary.
+
+You can run them individually, or all at once, with `run.sh`:
+
+    run.sh setup-all.yml
+
+If you're interested in setting up your own Forgejo service, this could be
+useful as a starting point, there's not much custom here! Just a couple things
+to note:
+
+- `setup-users.yml` contains my own username and my own SSH public keys—you'll
+  want to replace those! (Public SSH keys aren't secret, don't worry, I'm fine!)
+- `files/app.ini` includes some custom config you'll need to replace, like our
+  domain name. (We also opt to use Forgejo's built-in HTTPS support, via
+  Let's Encrypt!)
+- You'll need to create your own copy of the secret token files in
+  `files/secrets`. See the `README` in there for more details!
+- We used the latest version of Forgejo available at the time we deployed,
+  but it's possible you're reading this later. It's worth checking out
+  Forgejo's own self-hosting instructions, and making sure you download the
+  latest version.
+- This code is distributed under the GPLv3 license; see the `LICENSE` file for
+  more details.
+
+Hope this helps!
+
+[fj]: https://forgejo.org/

setup-all.yml

@@ -0,0 +1,4 @@
+---
+- import_playbook: setup-users.yml
+- import_playbook: setup-security.yml
+- import_playbook: setup-forgejo.yml