Merge branch 'docs-ldap-api-update' into 'master'

`provider` is always required - remove confusing text

See merge request gitlab-org/gitlab-ee!3889

doc/api/groups.md

@@ -536,7 +536,7 @@ Parameters:
 - `id` (required) - The ID of a group
 - `cn` (required) - The CN of a LDAP group
 - `group_access` (required) - Minimum access level for members of the LDAP group
-- `provider` (required) - LDAP provider for the LDAP group (when using several providers)
+- `provider` (required) - LDAP provider for the LDAP group
 
 ### Delete LDAP group link