Clarify when and how to enable new servers (neo4j#2623) (neo4j#2646)

- To document a missing step in the guide on how to deploy an analytics
cluster: you have to enable servers that are in the free state.
- To clarify the use and meaning of the initial settings when you deploy
a cluster for the first time.
- To add information about the setting, allowing automatic enabling of
free servers, to the section on the `ENABLED` state of servers.

---------

---------

Co-authored-by: Nick Giles <[email protected]>

Author: NataliaIvakina

modules/ROOT/pages/clustering/multi-region-deployment/multi-data-center-routing.adoc

@@ -58,7 +58,7 @@ Applying the same tag to multiple servers logically groups them together.
 Note that servers can have mulitple tags.
 
 Server tags are defined as a key that maps onto a set of servers in a cluster.
-Server tags are defined on each server using the  xref:configuration/configuration-settings.adoc#config_server.tags[`initial.server.tags`] parameter in _neo4j.conf_.
+Server tags are defined on each server using the  xref:configuration/configuration-settings.adoc#config_initial.server.tags[`initial.server.tags`] parameter in _neo4j.conf_.
 Each server in a cluster can be tagged with to zero or more server tags.
 Server tags can be altered at runtime via the `ALTER SERVER` command,
 see xref:clustering/servers.adoc#alter-server-options[Altering server options] for more details.

modules/ROOT/pages/clustering/servers.adoc

@@ -35,8 +35,19 @@ When first discovered, a server's name defaults to the value of its generated se
 [[server-enabled-state]]
 === Enabled state
 
-A server in the free state needs to be explicitly enabled in order to be considered an active member of the cluster.
-The command `ENABLE SERVER server name` is used to transition a server into this _Enabled_ state.
+When you deploy a cluster for the first time, at least the minimum number of servers included in the initial deployment are automatically enabled.
+For details, refer to the example on how to xref:clustering/setup/deploy.adoc#cluster-example-configure-a-three-primary-cluster[Configure a cluster with three servers].
+
+If you add a new server after the cluster is already running, the server is added in the `FREE` state.
+A server in the `FREE` state needs to be explicitly enabled in order to be considered an active member of the cluster.
+
+To transition a server into the _Enabled_ state, use the command `ENABLE SERVER`:
+
+[source, syntax, role=noheader]
+----
+ENABLE SERVER 'serverId' [OPTIONS "{" option: value[,...] "}"]
+----
+
 The server's initial name is its ID.
 If the server is already enabled and the command is executed with the same options, nothing is changed.
 
@@ -71,11 +82,30 @@ label:new[Introduced in 5.6]
 
 [NOTE]
 ====
-When a server is enabled, if no `OPTIONS` are not provided, the default server values are taken from the settings `initial.server.mode_constraint`, `initial.server.allowed_databases`, `initial.server.denied_databases`, and/or `initial.server.tags`.
+When a server is enabled, if no `OPTIONS` are provided, the default server's values are taken from the settings:
+
+* xref:configuration/configuration-settings.adoc#config_initial.server.mode_constraint[`initial.server.mode_constraint`]
+* xref:configuration/configuration-settings.adoc#config_initial.server.allowed_databases[`initial.server.allowed_databases`]
+* xref:configuration/configuration-settings.adoc#config_initial.server.denied_databases[`initial.server.denied_databases`]
+* and/or xref:configuration/configuration-settings.adoc#config_initial.server.tags[`initial.server.tags`]
+
+All these settings are only effective when enabling the relevant server.
 ====
 
+Another way to enable servers is to configure the DBMS automatically enable free servers.
+You can do this in one of two ways:
+
+* By setting xref:configuration/configuration-settings.adoc#config_initial.dbms.automatically_enable_free_servers[`initial.dbms.automatically_enable_free_servers`] to `true` before starting the deployment for the first time.
+* By running the following procedure after deployment:
++
+----
+CALL dbms.cluster.setAutomaticallyEnableFreeServers(true);
+----
+
 Once enabled, the server may be allocated databases to host.
 
+If you need to change some of the server's values, use the <<alter-server-options, `ALTER SERVER`>> command.
+
 
 
 [[deallocating-state]]