[chbot] ESP-32 Mongoose OS demo

[Robin Gilks]

I haven't followed this up and I should have done - thanks for the prompts
from a couple of people.

The code for the demo I did in December is now on github along with
instructions on how to build and flash it.

If you don't have a DHT22 sensor it will still prove instructive and it
will still do something.

It can be found at
   https://github.com/g8ecj/esp32_demo.git

Part of the process I've created in the README file suggests loading an
existing demo project from the Mongoose site to create the correct
directory structure. It's well worth playing with the suggested 'demo-js'
app as I used some of it in my code!!

-- 
Robin Gilks