Add documentation for web mercator and esri-leaflet-vector L.esri.Vector.vectorTileLayer

[jwasilgeo]

Wait until the next version of esri-leaflet-vector is released (after current 3.0.1)

https://github.com/Esri/esri-leaflet-vector/blob/master/CHANGELOG.md#upcoming-changes

[jwasilgeo]

https://github.com/Esri/esri-leaflet-vector/issues/86

https://github.com/Esri/esri-leaflet-vector/issues/94

[jwasilgeo]

This API docs page does a nice job explaining a similar requirement for another layer type: https://esri.github.io/esri-leaflet/api-reference/layers/tiled-map-layer.html

[pmacMaps]

Could the same text used on the Tile Map Layer page be used on the Vector Tile Layer page?

[jwasilgeo]

Patrick, sure thing, that's what I was thinking too. PRs welcome. 😸

For comparison here's the blurb I wrote in the vector plugin's readme: https://github.com/Esri/esri-leaflet-vector#lesrivectorvectortilelayer