Release 1.0.1

Added

• Link to instant-map example
• Add documentation in README
• Add "resetOverlayLayers" event listener

Changed

• Add .md extension to README
• Renamed UMD export from PrebakedLeafletMap to PrebakedGeoJSONMap
  (PrebakedLeafletMap was the original name, but felt less accurate).
  This is a breaking change, but this module doesn't have any users currently,
  so it's just being marked as a patch release.

Fixed

• Fix crashes for GeoJSON Features that don't include a "properties" key.