web serial firmware update tool added

[mofosyne]

Added the tool from https://github.com/dbuezas/arduino-web-uploader which is MIT licensed and allows for easily uploading prebuilt firmware from a chrome browser to an Arduino nano

[mofosyne]

Preview: https://mofosyne.github.io/jtag2updi/#loading-pre-built-hex-file-to-an-arduino-nano-using-web-serial

If I understand, the hex file is intended for an arduino nano. So here is a tool that allows you to upload it to an arduino nano via google chrome web browser.