Clarify geoprivacy terminology and guidance

[Star3]

@pisum

if the observer misses the warning messages telling them their observation may be missing location when they upload it

A one-time warning is easy to overlook. Maybe they intend to add the location later, but forgot.

Also, apparently people sometimes don’t even get the warning at all (from another thread):

@artemesia

I’ve accidentally left out locations a few times and it hasn’t told me during upload (usually whilst uploading on the go), and I see other serious iNatters doing the same thing often.