add usage info

README.md

@@ -8,3 +8,21 @@
 [![Release](https://img.shields.io/github/v/release/emeraldonion/odohd?style=for-the-badge)](https://github.com/emeraldonion/odohd/releases)
 
 This fork includes changes for a server suited to Emerald Onion's production deployment.
+
+## Usage:
+
+```
+Usage:
+  odohd [OPTIONS]
+
+Application Options:
+  -l, --listen=   Address to listen on (default: localhost:8080)
+  -r, --resolver= Target DNS resolver to query (default: 127.0.0.1:53)
+  -t, --no-tls    Disable TLS
+  -c, --cert=     TLS certificate file
+  -k, --key=      TLS key file
+  -v, --verbose   Enable verbose logging
+
+Help Options:
+  -h, --help      Show this help message
+```