Add blog posts about Binder federation member and docker stacks

[choldgraf]

This provides two draft blog posts to describe upstream impact that 2i2c has been involved with.

1. A historical post about our support for Docker Stacks (so that we have a record of this happening at all)
2. A short post describing the Hetzner experiment for a mybinder.org federation member

If either of these is controversial we can split this into 2 PRs but I thought it'd be easy-enough to add a quick stub post about Docker Stacks first.

[choldgraf]

I've updated the post to focus more on the single-node workflow rather than one specific cloud provider. I think the post should be ready to go whenever @yuvipanda thinks it's OK.

[yuvipanda]

Things to add if you so desire:

1. We added new functionality, to run our own registry backed by any kind of object storage. This has turned out to be extremely important - the registry is now already at 1.2 TB within a week! This is ok because the new (as in, released in december) hetzner object storage that we use costs 5 EUR / month / TB, compared to 23 USD / month / TB on AWS! Close to 5x cheaper. If hetzner hasn't released it, we'd have to manage storage ourselves and it would be more complex and expensive.

2. Final weight is 75% of traffic will come to this (25% to GESIS), to a max of 300 users: Increase 2i2c member weight one final time jupyterhub/mybinder.org-deploy#3196
3. This demonstrates why having a public realtime chat channel is extremely important - https://jupyter.zulipchat.com/#narrow/channel/469744-jupyterhub/topic/2i2c.20joining.20mybinder.2Eorg.20federation was instrumental in coordinating all the work that went into this. Thank Min and Simon.

[choldgraf]

@yuvipanda do you have any objection to me incorporating a quick round of feedback and then posting this on Monday?

[yuvipanda]

@choldgraf if you incorporate #356 (comment) you can post it on monday! don't need to wait for me

[choldgraf]

Woot ok that's my plan then

[choldgraf]

Do you have a link to a pr where we added that object storage functionality?

[yuvipanda]

@choldgraf ok, I actually take this back, I want to change this a little now that I've added another member. So hang on.

[rgaiacs]

Is the image duplicated?

[choldgraf]

Thanks everybody for the feedback. I incorporate some of the "landscape changes" that @yuvipanda mentioned, as well as the suggestions and edits from others. I also reframed this to be a bit more confident - I think that we can say this "experiment" is working and that we're already "in production" with this instance, so I've been clearer about this as well as the big picture of what this means.

I think this is ready to go from my perspective. Let me know if others have objections to posting it.

[yuvipanda]

Great job love it @choldgraf!

[choldgraf]

One more change, I've added rough price estimates for monthly usage for each of the major cloud providers, compared it to Hetzner, and turned this into a very rough price sketch to drive home our point. Here's the image for ref:

[choldgraf]

OK one more small change to the pricing after some better links from @yuvipanda and I think we're good to go. Thanks all for the feedback and iteration on this!