Add usage

Author: asnelzin

readme.md

@@ -1 +1,21 @@
 # WebSocket command line client
+
+> Simple WebSocket client for testing purposes
+
+## Usage
+
+```
+Usage:
+  ws [OPTIONS] URL
+
+Application Options:
+  -H, --header=  Custom HTTP header. You can specify as many as needed by repeating the flag.
+  -v, --version  Print the version information and exit
+
+Help Options:
+  -h, --help     Show this help message
+```
+
+## License
+
+MIT © [Alexander Nelzin](http://nelzin.ru)