epic: add section on formatters to examples page

[machow]

We can tweak the pieces below, but how about something like this:

• 3 column layout
• Let's plan on 6 examples to start (e.g. fmt_units, fmt_image, extc..)

The key to putting these on the examples page is that they'll need to be fairly compact. We want people to see a title (e.g. fmt_image() or that in human speak), along with the example, and to know right away roughly what it does.

Similar to reactable-py: