[DOCS] Fix typo (#319)

Author: jrodewig

docs/en/stack/security/authentication/ldap-realm.asciidoc

@@ -50,7 +50,7 @@ the expectation is that their roles are managed there as well. If fact, LDAP
 supports the notion of groups, which often represent user roles for different
 systems in the organization.
 
-The `ldap` realm enables you to map LDAP users to to roles via their LDAP
+The `ldap` realm enables you to map LDAP users to roles via their LDAP
 groups, or other metadata. This role mapping can be configured via the
 {ref}/security-api-put-role-mapping.html[add role mapping API] or by using a file stored
 on each node. When a user authenticates with LDAP, the privileges