Clarify GDS on Neo4j cluster in 5.x setup

Author: vnickolov

doc/modules/ROOT/pages/production-deployment/neo4j-cluster.adoc

@@ -23,8 +23,9 @@ Since GDS performs large computations with the full resources of the system it i
 We make use of a _Secondary_ instance to deploy the GDS library and process analytical workloads.
 Calls to GDS `write` procedures are internally directed via _server-side routing_ to the cluster instance that is a `Writer` for the database we work on.
 
-Neo4j 5.x supports different databases on the same machine to act as `Primary` or `Secondary` members of the cluster, we *do not* recommend mixed setup.
-GDS should be installed on a machine that is not serving transactional load and does not participate in `Leader` elections.
+Neo4j 5.x supports different databases on the same cluster instance to act as `Primary` or `Secondary` members of the cluster.
+In order for GDS to work correctly, all databases on the instance it is installed have to be `Secondary`, including the `system` database (see https://neo4j.com/docs/operations-manual/current/reference/configuration-settings/#config_server.cluster.system_database_mode[server.cluster.system_database_mode] and https://neo4j.com/docs/operations-manual/current/reference/configuration-settings/#config_initial.server.mode_constraint[initial.server.mode_constraint]).
+GDS has compute-intensive OLAP workloads that may disrupt the cluster operations and we recommend GDS to be installed on an instance that is not serving transactional load and does not participate in `Leader` elections.
 
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