feat: add release badges to doc status badges

[stevenle]

"pending releases" are cached via a context provider, when the doc status badges are rendered, it uses the cached values to prevent repeated db calls.

screenshots:

fixes #568

[jeremydw]

LGTM

One note - a doc could be in multiple releases technically. I wonder if we should make the badge just say "Release" and a popover that contains the release names, description, and a link to the releases?

[stevenle]

i'd like to keep the href within the badge itself since it's always tricky for me to have on-hover tooltips/menus that disappear if you're trying to rollover to it but took an unfavorable path causing the popover to disappear.

so two options:

1 - keep it as is (show a badge for each release, each clickable to to its respective release details page)
2 - show the message "N releases" with a tooltip that lists the ids, and when user clicks on it, it goes to a filtered version of the release list page which shows only the releases the doc is in

[jeremydw]

Let's go with either of your preferences for now - (1) seems simplest so sgtm and we can revise later