[mod] modified readme to include query string support

- considered experimental until more test coverage is done

README.md

@@ -48,7 +48,7 @@ http post $API_SERVER/admin/client $API_KEY <<< $JSON_REQUEST_BODY
 # Alternatively using query strings (be sure to encode special characters in the param values)
 API_KEY='X-API-Key=MdSUxrQQ.d5d40cd9.e2s1BsQEqmSE5MqyHYbDBVxGr/KY4BYIV5QkdjiCOF0='
 CLIENT_PARAMS='name=clientA&description=Client+across+the+river&permission=rw&public_ip=false'
-http post $API_SERVER/admin/client?$API_KEY&$CLIENT_PARAMS
+http post "$API_SERVER/admin/client?$API_KEY&$CLIENT_PARAMS"
 ```
 Updating a write client's `ipv4`:
 ```bash