This PR adds documentation for GeoIPv2 auto-update feature.
It also changes related settings names from geoip.downloader.* to ingest.geoip.downloader to have the same convention as current setting.
Relates to #68920
Co-authored-by: Elastic Machine <elasticmachine@users.noreply.github.com>
Co-authored-by: James Rodewig <40268737+jrodewig@users.noreply.github.com>
