add google news pwa

[bigboo3000]

Hi
Thanks for your add-on, I want to do the same with Google News PWA, I think I correctly modified your files to add Google News support but I can't test it.

[hyperstown]

Hi, sorry for a late response. As I mentioned in #4 (comment) there a few things that need to be considered when adding support to more websites.
However there's been quite a few people that asked me to enhance support beyond twitter.
That's why I'm working on new extension that will work on every website without need to manually add url of manifest.
So for now I'll neither merge nor close this PR. If for some reason I won't be able to complete that extension I'll start adding more websites to this one.
So in other words: If I mange to make a truly universal extension I'll close this PR and move all development to that one but if it proves to be impossible or with some major drawbacks I'll merge this PR and continue to add support to more websites.
As for ETA I hope to have first release by the end of the next week.