Documentation: clarifications for implementation of last_opened_time for apps table on macOS

The apps table on macOS relies on LaunchServices for application inventory information (when available), which is a very reliable system.

However, within that table, a single column (last_opened_time) relies on Spotlight instead - which is trivially disabled by users or configured to exclude entire directories.

I'm not sure where the best place for this documentation would be. Do we have standards on the lengths for descriptions of tables or columns within the tables? Most of the column descriptions seemed very uniform in length and it looked a little awkward (to me) to add "(if indexed by Spotlight)" to the column description.

Also - at a technical level, this metadata item is only valid for this specific application bundle. If the application is replaced/updated, Spotlight considers it a "new" app (which it technically is), for which the kMDItemLastUsedDate is no longer defined. I'm unsure if this limitation should also be clarified somewhere.

Start by locating the macOS apps table documentation and the last_opened_time column description. Check existing table and column description conventions, then clarify Spotlight indexing and the behavior when an application bundle is replaced; done when the documentation location and wording are agreed and both limitations are covered.