update README with all command-line options

README.md

@@ -29,6 +29,18 @@ variable (preferred over the `-password` flag, which is visible in process
 listings). Use `-password-prompt` to read the password interactively from
 stdin.
 
+## Options
+
+- `-server host[:port]` — server to connect to (default: `localhost:64738`)
+- `-username name` — client username
+- `-password pass` — server password (prefer `MUMBLE_PASSWORD` env var)
+- `-password-prompt` — prompt for password on stdin
+- `-certificate path` — PEM encoded certificate and private key
+- `-insecure` — skip server certificate verification
+- `-tree-width n` — width of the channel tree pane (default: `20`)
+- `-log path` — append chat messages to file
+- `-debug` — enable debug logging to stderr
+
 ## Manual
 
 ### Key bindings