Fix: delete iperf-client example.

The sketch was for modified for internal purposes from the official TC6 example code but is not relevant for the libraries target audience. Also it never really worked.

Author: aentinger

Diff for: README.md

@@ -9,7 +9,7 @@
 
 ### How-to-compile/upload
 ```bash
-arduino-cli compile -b arduino:renesas_uno:unor4wifi -v examples/iperf-client -u -p /dev/ttyACM0
+arduino-cli compile -b arduino:renesas_uno:unor4wifi -v examples/UDP_Client -u -p /dev/ttyACM0
 ```
 
 ### How-to-[`EVB-LAN8670-USB`](https://www.microchip.com/en-us/development-tool/EV08L38A)