docs(authentication): add new file option to readme (#338)

README.md

@@ -280,16 +280,21 @@ If the configuration file is not found in the current directory, specify it via
 $ CONFIG="$HOME/.rustypaste.toml" rustypaste
 ```
 
+#### Authentication
+
 To enable basic HTTP auth, set the `AUTH_TOKEN` environment variable (via `.env`):
 
 ```sh
 $ echo "AUTH_TOKEN=$(openssl rand -base64 16)" > .env
 $ rustypaste
 ```
 
-You can also set multiple auth tokens via the array field `[server].auth_tokens` in your `config.toml`.
+There are 2 options for setting multiple auth tokens:
+
+- Via the array field `[server].auth_tokens` in your `config.toml`.
+- Or by writing a newline separated list to a file and passing its path to rustypaste via `AUTH_FILE` and `DELETION_FILE` respectively.
 
-> If neither `AUTH_TOKEN` nor `[server].auth_tokens` are set, the server will not require any authentication.
+> If neither `AUTH_TOKEN`, `AUTH_FILE` nor `[server].auth_tokens` are set, the server will not require any authentication.
 >
 > Exception is the `DELETE` endpoint, which requires at least one token to be set. See [deleting files from server](#delete-file-from-server) for more information.