doc: add companion pc tools

README.md

@@ -76,9 +76,16 @@ Or simply use make.
 
     $ make flash
 
-## Control from PC
+## Companion Tools
 
-See [python directory](/python/README.md).
+There are seveal numbers of great companion PC tools from third-party.
+
+* [NanoVNASharp Windows software](https://drive.google.com/drive/folders/1IZEtx2YdqchaTO8Aa9QbhQ8g_Pr5iNhr) by hugen79
+* [NanoVNA WebSerial/WebUSB](https://github.com/cho45/NanoVNA-WebUSB-Client) by cho45
+* [Android NanoVNA app](https://play.google.com/store/apps/details?id=net.lowreal.nanovnawebapp) by cho45
+* [NanoVNASaver](https://github.com/mihtjel/nanovna-saver) by mihtjel
+* [TAPR VNAR4](https://groups.io/g/nanovna-users/files/NanoVNA%20PC%20Software/TAPR%20VNA) supports NanoVNA by erikkaashoek
+* see [python](/python/README.md) directory to use NanoVNA with Python and Jupyter Notebook.
 
 
 ## Note