Add greetings action

[kudoabhijeet]

Add a Github Action for greeting new contributors with :

1. New PRs
2. New Issues

[khushi0704]

Hey , is this issue sill open ? I want to work on this issue for nwoc ! But I don't know how to do it . Can you guide me ? I can ensure I ' ll work hardly !

[subhangi2731]

can you please assign this issue to me? @kudoabhijeet

[musavveer]

If the issue is resolved please close the issue.