Add README about how to use CI scripts for local development setup on windows

[pramodk]

One of the pending action item from #572

• add README about how to use CI scripts for local development setup on windows

• In terms of implementation, this is complete. Tomorrow I will finalise / polish some bits and write instructions for how one can setup entire development environment. Only changes that will affect your setup is changes in mingw_files/vcenv.sh. But in the document tomorrow I will write instructions so that we can get uniform setup.
• I am bit sloppy with the batch scripts due to lack of windows experience.
• I am creating this as Draft because I would like to make some improvements tomorrow