the 'using construct is not .experimental anymore

compiler/semstmts.nim

@@ -437,8 +437,6 @@ proc isDiscardUnderscore(v: PSym): bool =
 proc semUsing(c: PContext; n: PNode): PNode =
   result = ast.emptyNode
   if not isTopLevel(c): localError(n.info, errXOnlyAtModuleScope, "using")
-  if not experimentalMode(c):
-    localError(n.info, "use the {.experimental.} pragma to enable 'using'")
   for i in countup(0, sonsLen(n)-1):
     var a = n.sons[i]
     if gCmd == cmdIdeTools: suggestStmt(c, a)

doc/manual/stmts.txt

@@ -547,9 +547,6 @@ Instead of:
 Using statement
 ---------------
 
-**Warning**: The ``using`` statement is experimental and has to be
-explicitly enabled with the `experimental`:idx: pragma or command line option!
-
 The using statement provides syntactic convenience in modules where
 the same parameter names and types are used over and over. Instead of:
 
@@ -563,7 +560,6 @@ name ``c`` should default to type ``Context``, ``n`` should default to
 ``Node`` etc.:
 
 .. code-block:: nim
-  {.experimental.}
   using
     c: Context
     n: Node