Add registered country fields

to the city, country, and enterprise databases

Author: joegallo

docs/changelog/114521.yaml

@@ -0,0 +1,5 @@
+pr: 114521
+summary: Add support for registered country fields for maxmind geoip databases
+area: Ingest Node
+type: enhancement
+issues: []

docs/reference/ingest/processors/geoip.asciidoc

@@ -51,10 +51,12 @@ field instead.
 *Depends on what is available in `database_file`:
 
 * If a GeoLite2 City or GeoIP2 City database is used, then the following fields may be added under the `target_field`: `ip`,
-`country_iso_code`, `country_name`, `country_in_european_union`, `continent_code`, `continent_name`, `region_iso_code`, `region_name`, `city_name`, `postal_code`, `timezone`,
+`country_iso_code`, `country_name`, `country_in_european_union`, `registered_country_iso_code`, `registered_country_name`, `registered_country_in_european_union`,
+`continent_code`, `continent_name`, `region_iso_code`, `region_name`, `city_name`, `postal_code`, `timezone`,
 `location`, and `accuracy_radius`. The fields actually added depend on what has been found and which properties were configured in `properties`.
 * If a GeoLite2 Country or GeoIP2 Country database is used, then the following fields may be added under the `target_field`: `ip`,
-`country_iso_code`, `country_name`, `country_in_european_union`, `continent_code`, and `continent_name`. The fields actually added depend on what has been found
+`country_iso_code`, `country_name`, `country_in_european_union`, `registered_country_iso_code`, `registered_country_name`, `registered_country_in_european_union`,
+`continent_code`, and `continent_name`. The fields actually added depend on what has been found
 and which properties were configured in `properties`.
 * If the GeoLite2 ASN database is used, then the following fields may be added under the `target_field`: `ip`,
 `asn`, `organization_name` and `network`. The fields actually added depend on what has been found and which properties were configured
@@ -70,7 +72,8 @@ The fields actually added depend on what has been found and which properties wer
 `organization_name`, `network`, `isp`, `isp_organization_name`, `mobile_country_code`, and `mobile_network_code`. The fields actually added
 depend on what has been found and which properties were configured in `properties`.
 * If the GeoIP2 Enterprise database is used, then the following fields may be added under the `target_field`: `ip`,
-`country_iso_code`, `country_name`, `country_in_european_union`, `continent_code`, `continent_name`, `region_iso_code`, `region_name`, `city_name`, `postal_code`, `timezone`,
+`country_iso_code`, `country_name`, `country_in_european_union`, `registered_country_iso_code`, `registered_country_name`, `registered_country_in_european_union`,
+`continent_code`, `continent_name`, `region_iso_code`, `region_name`, `city_name`, `postal_code`, `timezone`,
 `location`, `accuracy_radius`, `country_confidence`, `city_confidence`, `postal_confidence`, `asn`, `organization_name`, `network`,
 `hosting_provider`, `tor_exit_node`, `anonymous_vpn`, `anonymous`, `public_proxy`,
 `residential_proxy`, `domain`, `isp`, `isp_organization_name`, `mobile_country_code`, `mobile_network_code`, `user_type`, and