Newsletter: Create template and document workflow

[ozkriff]

I propose publishing the first newsletter on September 2. After its release, I'm going to strip it down to a bare-bones template (like it's done in embedded WG, for example) and add it to the repo so we can start working in the second newsletter.

In #9 (comment) I've partly mentioned how the collective newsletter creation process could be organized, at what publishing dates we are aiming, etc. This workflow question is closely linked to the creation of the next newsletter and it needs to be discussed and documented (in README, I guess), so I'm going add this to the PR too.

Related to #2 ("Newsletter")

[17cupsofcoffee]

I think the workflow you described in the link sounds good, if no one has any objections.