Doc changes needed for enable security-manager property

Community member Eric Shu reports:
Here is the description for enable security properties: (https://geode.apache.org/docs/guide/114/managing/security/enable_security.html)

security-manager Property
The authentication callback and the authorization callback that implement the SecurityManager interface are specified with the security-manager property. When this property is defined, authentication and authorization are enabled. The definition of the security-manager property is the fully qualified name of the class that implements the SecurityManager interface. For example:

security-manager = com.example.security.MySecurityManager
To ensure that the security-manager property is applied consistently across a cluster, follow these guidelines:

Specify the security-manager property in a properties file, such as gemfire.properties, not in a cluster configuration file (such as cluster.properties).
Specify the properties file when you start the first locator for the cluster. The locator will propagate the value to all members (locators and servers) that follow.
If you must specify the security-manager property for servers (neither necessary nor recommended) make sure its value is exactly identical to that specified for the first locator.

This is true if the cluster has enabled the cluster configuration service, and new members have set the `use-cluster-configuration=true`.

Documentation should explain that if cluster configuration is not enabled, you must specify the security-manager property for servers, makng sure its value is exactly identical to that specified for the first locator.