Updating terminology used when describing the privileges kibana_user has (#340)

* Changing the built-in role description

* Changing phrasing about minimum privileges

Author: kobelb

docs/en/stack/security/authorization/built-in-roles.asciidoc

@@ -56,8 +56,8 @@ NOTE: This role should not be assigned to users as the granted permissions may
 change between releases.
 
 [[built-in-roles-kibana-user]] `kibana_user`::
-Grants the privileges required for users of {kib}. This role grants access to Kibana
-and grants monitoring privileges for the cluster.
+Grants access to all features in {kib}. For more information on Kibana authorization,
+see {kibana-ref}/xpack-security-authorization.html[Kibana Authorization].
 
 [[built-in-roles-logstash-admin]] `logstash_admin` ::
 Grants access to the `.logstash*` indices for managing configurations.

docs/en/stack/security/get-started-security.asciidoc

@@ -153,7 +153,8 @@ role and save the change. For example:
 [role="screenshot"]
 image::security/images/assign-role.jpg["Assigning a role to a user in Kibana"]
 
-This user now has the minimum privileges required to use {kib}. 
+This user now has access to all features in {kib}. For more information about granting
+access to Kibana see {kibana-ref}/xpack-security-authorization.html[Kibana Authorization].
 
 If you completed all of the steps in 
 {stack-gs}/get-started-elastic-stack.html[Getting started with the {stack}], you should