removed section on aggregation opt-in

Author: rsill-neo4j

modules/ROOT/pages/guides/v4-migration/index.adoc

@@ -559,27 +559,6 @@ const neoSchema = new Neo4jGraphQL({
 })
 ----
 
-[[opt-in-aggregation]]
-=== Opt-in Aggregation
-
-Aggregation operations are no longer generated by default.
-They can be enabled case by case using the directives xref::type-definitions/schema-configuration/type-configuration.adoc#_query[`@query`] and xref::type-definitions/schema-configuration/field-configuration.adoc#_relationship[`@relationship`].
-
-
-You can enable the operation fields `actorsAggregate` and `actedInAggregate` like this:
-
-[source, graphql, indent=0]
-----
-type Movie {
-  title: String!
-}
-
-type Actor @query(aggregate: true) {
-  name: String!
-  actedIn: [Movie!]! @relationship(type: "ACTED_IN", direction: OUT, aggregate: true) 
-}
-----
-
 === Session configuration
 
 Session configuration is now available only in the context under the `sessionConfig` key.