[DOCS] clarify v7 file realm configuration (#94778)

* [DOCS] clarify v7 file realm configuration

* Update x-pack/docs/en/security/authentication/configuring-file-realm.asciidoc

Co-authored-by: Yang Wang <[email protected]>

---------

Co-authored-by: Yang Wang <[email protected]>

Author: abdonpijpelink

x-pack/docs/en/security/authentication/configuring-file-realm.asciidoc

@@ -1,3 +1,14 @@
+To use the `file` or `native` realms when any other realms are configured and
+enabled, you need to explicitly configure them in the `elasticsearch.yml` file.
+
+If no other realms are configured and enabled, you don't need to explicitly
+configure a `file` or `native` realm and they are added to the realm
+chain by default.  Unless configured otherwise, the `file` realm is added
+first, followed by the `native` realm.
+
+IMPORTANT: While it is possible to define multiple instances of some other
+realms, you can define only _one_ `file` realm per node.
+
 All the data about the users for the `file` realm is stored in two files on each 
 node in the cluster: `users` and `users_roles`. Both files are located in 
 `ES_PATH_CONF` and are read on startup.
@@ -14,9 +25,6 @@ files distributed or copied to all other nodes in the cluster (either manually
 or using a configuration management system such as Puppet or Chef).
 ==============================
 
-The `file` realm is added to the realm chain by default. You don't need to
-explicitly configure a `file` realm.
-
 . (Optional) Add a realm configuration to `elasticsearch.yml` under the
 `xpack.security.authc.realms.file` namespace. At a minimum, you must set 
 the realm's `order` attribute.

x-pack/docs/en/security/authentication/file-realm.asciidoc

@@ -19,11 +19,6 @@ In this type of scenario, the `file` realm is a convenient way out - you can
 define a new `admin` user in the `file` realm and use it to log in and reset the
 credentials of all other users.
 
-IMPORTANT: When you configure realms in `elasticsearch.yml`, only the realms you
-specify are used for authentication. To use the `file` realm you must explicitly
-include it in the realm chain. While it is possible to define multiple instances
-of some other realms, you can define only _one_ file realm per node.
-
 To define users, the {security-features} provide the
 {ref}/users-command.html[users] command-line tool. This tool enables you to add
 and remove users, assign user roles, and manage user passwords.