WeightedLocation should be noted in the heatmap docs

[timhuff]

I'm making a heat map of the aggregation of a ton of data. When I came across the example, I went "...wait, so I have to send all my data points across the wire??". I don't know how you guys have your docs set up or else I'd put the pull request in myself. But if you simply added "note: for large amounts of data, you can utilize google.maps.visualization.WeightedLocation in place of google.maps.LatLng", I think it'd really help people. I had to go digging in the source code to see if there was a way I could get around sending every data point.

[JustFly1984]

@timhuff this package is unmaintained over 4 years. please use @react-google-maps/api instead.