Document way to get a count of a search you are about to do.

[cholmes]

It's often nice to just see how many results a search will return, instead of running the full results.

In v1 planet data search download --dry-run would provide this. Not sure exactly how.

I will note it's likely possible to do this with planet data stats - but we should at least have an example / docs on how to get the call with just the total count (like not in buckets, just totaling up). Probably can just do some cli magic for it.

[jreiberkyle]

cli magic:
planet data search --limit 0 --filter filter.json PSScene | wc -l

changing this to a doc ticket.

[cholmes]

planet data search --limit 0 --filter filter.json PSScene | wc -l

That's going to be a really heavy call for things like 'PSScene all time collects', which is one of the common things that I do. Like it'd take hours if not days. I was thinking more planet data stats and then use jq to extract the count for each year and then add up all the counts.

[cholmes]

Figured this out: jq '.buckets | map(.count) | add'!

It's included in #891 PR.

[JuLeeAtPlanet]

As noted above: included in #891 PR.