2021 Media markdown

[eeeps]

Markdownifying the google doc. WIP!

Makes progress on #2144

Staging: https://20211207t160821-dot-webalmanac.uk.r.appspot.com/en/2021/media

[tunetheweb]

I've cleaned it up a little and staged it here: https://20211207t160821-dot-webalmanac.uk.r.appspot.com/en/2021/media (also added to the top comment). This doesn't auto update btw so need to reach out to update that occassionally.

[tunetheweb]

Not had a chance to go through this fully yet, but have some light feedback already so might as well get you started on those!

[eeeps]

@tunetheweb oops, I missed the "30 hidden conversations" Github collapsed in the middle of your review!

Stole some time today to address all of the easy ones in the Images section. I'll try to make as much headway on the meatier things as I can over the next couple of days before I'm fully back on Monday.

I'll ping @dougsillars about your proposed changes to Video.

Thanks again @tunetheweb !! Extremely valuable feedback! Should we credit you as editor?

[eeeps]

Ok, from my perspective, the final remaining tasks are:

• decide whether to delete the "srcset resource densities" section. I'm in favor, but @tunetheweb if you think there's valuable insight here that's worth clarifying, I'm game to give it another go
• possibly convert the video chart showing absolute counts to use percentages @dougsillars
• possibly re-write the bit about default video aspect ratios @dougsillars
• re-run the chart-PNG-generating Puppeteer script, and replace the updated charts in src/static/images/2021/media/

[tunetheweb]

OK I've taken care of a couple of those things and left TODOs in place for the other two. We can pick them up in editing PR.

@dougsillars I had rewrite some of your queries and also had to change some of your preload text as it looks like there wasn't a switch from auto but more a move away from using preload at all.

I've updated the staging link at the top if you want to have a look.

I'm now going to merge this now, then do a quick copy edit later today or tomorrow and open the PR and then, if you accept that, we're done and can launch!