Add info icon to show the meta data for the relevant overlay

Currently, the overlays stand alone without context. The users suggested a small information icon next to each overlay could be included to provide a brief description of the layer. On click, a small popup should appear with this brief description and should disappear after a small delay on mouse away or immediately on click away.

This requires that each layer come with a description tailored towards the users. Whether this popup could include a link to relevant sources/authors should be considered but is beyond the scope of this story. Styling of the popup should remain consistent with that of the current site and should avoid hindering user interaction with the map or drawer

Start by locating the overlay and layer rendering entry points, then inspect the current site's popup styling and map or drawer interaction patterns. Done means every layer has a user-facing description, an information icon opens it, and the popup closes on mouse away after a delay or immediately on click away; source and author links are out of scope.