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

Co-authored-by: Lisa Cawley <[email protected]>

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

@@ -22,7 +22,7 @@ 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, it is only possible to define _one_ file realm per node.
+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