documented new .this pragma

doc/manual/stmts.txt

@@ -577,6 +577,9 @@ name ``c`` should default to type ``Context``, ``n`` should default to
 The ``using`` section uses the same indentation based grouping syntax as
 a ``var`` or ``let`` section.
 
+Note that ``using`` is not applied for ``template`` since untyped template
+parameters default to the type ``system.untyped``.
+
 
 If expression
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