docs: 📝 add README with feature list, deployment instructions and contribution guidelines

- Add LICENSE
- Improve sample config with comments and corresponding env vars

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2023 [fullname]
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -1,3 +1,79 @@
 # Listy
 
-A Go application that syncs your liked songs into a monthly playlist.
+A web application that syncs your liked songs into a monthly playlist built with Go.
+
+## Features
+
+- Spotify OIDC for authentication
+- Automatically create a monthly playlist following the naming scheme `YYYY MM`
+- Sync songs from your liked playlist to the current monthly playlist
+- Reuse playlists following the same naming scheme
+- Run the sync script as a one-time command (`listy sync`) or on a time (`listy sync -r 5m`)
+
+## Deployment
+
+Listy can be run as a self-hosted application as a Docker container or with Go installed.
+
+### Create a Spotify application
+
+Head to the [Spotify API dashboard](https://developer.spotify.com/dashboard) and create your application. Call it "Listy" and take note of the generated client ID and secret.
+
+Add the following redirect URI to the application to enable OIDC auth:
+
+http(s)://listy.example.com/auth/oidc/spotify/callback
+
+### Listy configuration
+
+Listy can be configured with environment variables or a config file, placed at the location of the binary or in one of the supported locations found in [`main.go`](./main.go).
+
+The following configuration values are supported:
+
+```yml
+spotify:
+  # Spotify OIDC client ID
+  clientId: <SPOTIFY_CLIENT_ID>
+  # Spotify OIDC client secret
+  clientSecret: <SPOTIFY_CLIENT_SECRET>
+mongodb:
+  # MongoDB connection URI
+  uri: <MONGODB_URI>
+server:
+  # session key used for cookie sessions, ideally a random string with at least 32 characters
+  sessionKey: <SERVER_SESSION_KEY>
+  # server scheme, either http or https
+  scheme: <SERVER_SCHEME>
+  # server host, such as localhost:5001 or listy.example.com
+  host: <SERVER_HOST>
+```
+
+#### Support for environment variables
+
+Listy supports environment variables corresponding to the names in the `<>` in the example file above.
+
+### With Docker Compose
+
+Listy can be deployed with Docker compose, and simply requires a MongoDB instance and the configuration file to work.
+
+To deploy your Listy instance, copy the [`docker-compose.yml`](./docker-compose.yml) and optionally create a `.env` file for your sensitive values. The sample config is also provided at [`config.example.yml`](./config.example.yml).
+
+Finally, run the following in the folder where your `docker-compose.yml` and `config.yml` are:
+
+```sh
+$ docker compose up -d
+```
+
+## License
+
+Listy is licensed under the [MIT license](./LICENSE).
+
+## Contributions
+
+Contributions are welcome, all code must simply pass CI. Contribution guidelines still WIP.
+
+## Roadmap
+
+Some more features are planned, including:
+
+- [ ] Optionally copying over songs from previous monthly lists
+- [ ] Notifications
+- [ ] Management UI

config.example.yml

@@ -1,8 +1,15 @@
 spotify:
+  # Spotify OIDC client ID
   clientId: <SPOTIFY_CLIENT_ID>
+  # Spotify OIDC client secret
   clientSecret: <SPOTIFY_CLIENT_SECRET>
+mongodb:
+  # MongoDB connection URI
+  uri: <MONGODB_URI>
 server:
-  sessionKey: <RANDOM_STRING_VALUE>
-  # set these values if server is accessed via a domain
-  # scheme: https
-  # host: listy.example.com
+  # session key used for cookie sessions, ideally a random string with at least 32 characters
+  sessionKey: <SERVER_SESSION_KEY>
+  # server scheme, either http or https
+  scheme: <SERVER_SCHEME>
+  # server host, such as localhost:5001 or listy.example.com
+  host: <SERVER_HOST>