Swift: add more doc strings to generated things

misc/codegen/templates/ql_class.mustache

@@ -1,9 +1,7 @@
 // generated by {{generator}}
 /**
  * This module provides the generated definition of `{{name}}`.
-{{#ql_internal}}
- * INTERNAL: Do not use.
-{{/ql_internal}}
+ * INTERNAL: Do not use. Import the corresponding module under `elements` instead.
  */
 
 private import {{import_prefix}}.Synth
@@ -13,16 +11,12 @@ import {{.}}
 {{/imports}}
 
 module Generated {
-  {{#has_doc}}
   /**
-  {{#ql_internal}}
-   * INTERNAL: Do not use.
-  {{/ql_internal}}
   {{#doc}}
    * {{.}}
   {{/doc}}
+   * INTERNAL: Do not use. Use the wrapper class under `elements` instead.
    */
-  {{/has_doc}}
   class {{name}} extends Synth::T{{name}}{{#bases}}, {{.}}{{/bases}} {
   {{#root}}
     /**