GeoMap Documentation - Transformations

Add documentation for GeoMap Transformations Conall Ó Gribín :apple: [1 hour ago](https://raintank-corp.slack.com/archives/C04J73AAQ87/p1680691442436399) Hi, I notice we added support for spatial transformations to the geomap panel via this PR: https://github.com/grafana/grafana/pull/44020 At present there is no public facing documentation on this transformation type, and we are starting to get support cases where this transform is being applied (e.g when using the [snapshot option](https://grafana.com/docs/grafana/latest/dashboards/share-dashboards-panels/#publish-a-snapshot) on a dashboard where a geomap panel is present.) It would be great if we could get some explanation written up and added to the list of available transformation functions for our customers; can anyone help with this? https://grafana.com/docs/grafana/latest/panels-visualizations/query-transform-data/transform-data/#transformation-functions (edited)