docs(README): Update README on contributing section

[lsetiawan]

Added contributors images directly from contributor graph. Update text to move Brandon to previous dev. Also bump the copyright date.

[emiliom]

I like the addition of those contributor thumbnails and link to the graph! Thanks also for the other updates.

I approve. But I'd make the same text updates to the docs (index page and copyright in config file), while we're at it.

[emiliom]

Thanks @lsetiawan ! See my comments.