Blog should either have a license statement, or we should decide it won't have a license

[paulproteus]

A nice person asks in #userops:

paulproteus, what is the license of that image at the top of the page

We should choose a license for the blog content. I propose we license it as CC Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/. We should probably add a clear trademark statement somewhere, too. I can make a wiki page called "Blog license" or something to address this.

@kentonv @jadeqwang requesting your +1 or -1 on CC Attribution 4.0 International.

[kentonv]

Seems reasonable.