Add Lighthouse Badge to Readme

[lukeed]

See example.

Applies to all official readmes

[alejandronanez]

I'd like to work on this, would it be possible?
Thanks!

[reznord]

Sure, go ahead :)

[alejandronanez]

Thanks @reznord ! I'll create the PR this weekend!

[alejandronanez]

Hey @reznord I have a question, where can I find that badge? I searched on shields.io but didn't find it.
Thanks!

[developit]

It's custom @alejandronanez. Should just be able to use the URL @lukeed provided.

[amitsarangi]

I believe this can be closed :)