docs: minor adjustments for stdcall removal

This commit include minor adjustments of documentation related to
stdcall removal.

docs/users_guide/using-warnings.rst

@@ -694,8 +694,7 @@ of ``-W(no-)*``.
 
     Causes a warning to be emitted for foreign declarations that use
     unsupported calling conventions. In particular, if the ``stdcall``
-    calling convention is used on an architecture other than i386 then
-    it will be treated as ``ccall``.
+    calling convention is used then it will be treated as ``ccall``.
 
 .. ghc-flag:: -Wdodgy-foreign-imports
     :shortdesc: warn about dodgy foreign imports

docs/users_guide/win32-dlls.rst

@@ -319,7 +319,7 @@ to call from the outside. For example:
     adder :: Int -> Int -> IO Int  -- gratuitous use of IO
     adder x y = return (x+y)
 
-    foreign export stdcall adder :: Int -> Int -> IO Int
+    foreign export ccall adder :: Int -> Int -> IO Int
 
 Add some helper code that starts up and shuts down the Haskell RTS: