Add PR welcoming badge

[jamesgeorge007]

I think it's good to have a PR welcoming badge within the README file 🤔
As per now I made it to point to the Pr's section.

But it's a good idea to have a contributing.md file to which it should be pointed.

[codecov]

Codecov Report

Merging #1291 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master   #1291   +/-   ##
======================================
  Coverage     100%    100%           
======================================
  Files           5       5           
  Lines         393     393           
======================================
  Hits          393     393

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