PR to document Explore Metrics (previously datatrails) (#85212)
* text dump
* initial edits
* more edits
* added more info, made edits
* first draft
* removed some commented out content
* final edits
* made requested changes
* feature name change
* missed a metrics explore - fixed
* ran prettier
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Co-authored-by: lwandz13 <larissa.wandzura@grafana.com>
(cherry picked from commit 3721682a02)
Co-authored-by: Eve Meelan <81647476+Eve832@users.noreply.github.com>