Renamed example file to fit PlatformIO, added detailed quickstart

[ibaranov-cp]

Open to comments, change requests, etc. Should be on 0.8.4

[PhracturedBlue]

I'm not really keen to rename credentials.h.example. There are 2 reasons:

1. It makes it more difficult for me to maintain the code, as I need to keep the template version as well as the version I actually use for day-to-day testing and make sure I switch between them before and after each commit.

2. You can't use the file as is regardless

[austonpramodh]

This is actually helpful...

[austonpramodh]

BUt I still dont understand how to use send_ota.py or how to start with it...please help

[shajek]

Something like this python.exe send_ota.py --bin firmware.bin --broker your.broker.eu --user test --password test123 --topic esp8266- --node 123ef12