docs: clearify that both ip4 and ip6 addresses are supported

docs/plugins/ingest-geoip.asciidoc

@@ -2,7 +2,8 @@
 === Ingest Geoip Processor Plugin
 
 The GeoIP processor adds information about the geographical location of IP addresses, based on data from the Maxmind databases.
-This processor adds this information by default under the `geoip` field.
+This processor adds this information by default under the `geoip` field. The `geoip` processor can resolve both IPv4 and
+IPv6 addresses.
 
 The ingest-geoip plugin ships by default with the GeoLite2 City and GeoLite2 Country geoip2 databases from Maxmind made available
 under the CCA-ShareAlike 3.0 license. For more details see, http://dev.maxmind.com/geoip/geoip2/geolite2/