Add location of docs Github to readme and contributions page

[Kris-Martin]

Hi,

I think it would be helpful to add a link to the Github for the docs website in the testng readme and the testng contributions page so that people can more easily contribute to updating the docs website - assuming you would like to encourage people to do that.

testNG docs website

[juherr]

👍

Could you propose a pull request to fix that?

[mohsinsackeer]

#2946
I have created a pull request for this. Please check it out.