add documentation for jwt token (#28)

Co-authored-by: Taran Romana <[email protected]>

README.md

@@ -112,6 +112,16 @@ The library provides multiple ways to interact with it. The quick start example
          </script>
 ```
 
+When using jwt authentication we just need to have jwt token in authentication section.
+If jwt token is used, username and password will be ignored.
+
+```
+   authentication: {
+      jwt: "jwt_token"
+   },
+
+```
+
 > This assumes the HTML body will contain empty elements with the IDs "dialpad", "call_list", "call_control", "media_devices", "audio_context" and "user_agent" where the corresponding default elements should be generated by libwebphone.
 
 ## NPM Scripts