add srcds-tf2 to readme

README.md

@@ -11,6 +11,32 @@ The following is currently packaged:
 - `metamod-source`
 - `sourcemod`
 - [`sourcemod-include-library`](https://github.com/JoinedSenses/SourceMod-IncludeLibrary)
+- `srcds-tf2`
+
+## TF2 Dedicated server
+
+The `srcds-tf2` package contains the TF2 dedicated server.
+
+You can start a basic server with
+`nix run .#srcds-tf2 -- -enablefakeip +map cp_badlands`, once it's done loading
+you can get the SDR ip using `status` (it will start with `169.254`), and
+connect to it from your client.
+
+### Writable tf directory
+
+When running the server directly from the nix store, the tf directory will be
+read only. Which is likely to cause issues as various things try to write to the
+directory during normal operations. To work around this, you can either copy it
+out of the nix store into a normal directory and make it writable, setup a
+writable overlayfs, or try to configure tf2 to only write outside the tf
+directory (unsure if this is feasible).
+
+### Maps
+
+To save space, `cp_badlands` is the only map bundled with `srcds-tf2`. If you
+need additional maps you need to either manually add them to the server, or use
+a plugin like [`mapdownloader`](https://codeberg.org/spire/mapdownloader) to
+automatically download maps on demand;
 
 ## Sourcemod SDKs