Fix SAML resource example

Author: timofurrer

docs/resources/group_saml_link.md

@@ -18,7 +18,7 @@ The `gitlab_group_saml_link` resource allows to manage the lifecycle of an SAML
 ```terraform
 resource "gitlab_group_saml_link" "test" {
   group_id        = "12345"
-  access_level    = "Developer"
+  access_level    = "developer"
   saml_group_name = "samlgroupname1"
 }
 ```

examples/resources/gitlab_group_saml_link/resource.tf

@@ -1,5 +1,5 @@
 resource "gitlab_group_saml_link" "test" {
   group_id        = "12345"
-  access_level    = "Developer"
+  access_level    = "developer"
   saml_group_name = "samlgroupname1"
 }