Integrate Welcome Bot

[tharunc]

Hello there,
I can add a welcome bot config file having a proper message that will show up when any user will open up an issue or pull-request for the first time as a part of DWOC.
Please assign me this issue.
For reference, kindly check out: https://github.com/apps/welcome

THANK YOU

[born-2learn]

Would you still like to work on this @tharunc ?