Document configuration

README.md

@@ -1,3 +1,34 @@
 # diodemail
 
 Send-only smtp server
+
+## Configuration
+
+Configuration is done through a json file. By default it will read
+from `/etc/diodemail/config.json`, but this can be overridden by
+passing the `--config-file` program argument. The only other
+program argument is the `--log-level` which can be one of the
+below options.
+
+```json
+{
+	"LogLevel": "the minimum level to log", // one of trace, debug, info, warn, error, fatal, or panic (default: info)
+	"Host":     "your.domain.here", // the hostname to send mail from (the part after the @ in outgoing email)
+	"Ports": {
+		"Plain": "##" or "disabled", // the port number to listen on or disabled to not listen with plain text
+		"TLS": "##" or "disabled" // the port nmuber to listen on or disabled to not listen with TLS
+	},
+	"Certificate": {
+		"CertFile": "path/to/the/cert/file",
+		"KeyFile": "path/to/the/private/key/file"
+	},
+	"Auth": {
+		"Enabled": true or false, // Default true
+		"PasswordHash": "" // sha256 hash of \0username\0password
+	}
+}
+```
+
+## diodemail-hash
+
+The included `diodemail-hash` shell script is useful for generating the `PasswordHash`