help/config: remove outdated false claim about pywin32

Since version 1.8 (released on 2011-03-01), Mercurial doesn't use pywin32 any
more. The old fallback mechanism to use C:\Mercurial\Mercurial.ini if pywin32 is
not installed was removed in 244772f67ac1.

mercurial/help/config.txt

@@ -83,9 +83,7 b' ones.'
     keys contain PATH-like strings, every part of which must reference
     a ``Mercurial.ini`` file or be a directory where ``*.rc`` files will
     be read.  Mercurial checks each of these locations in the specified
-    order until one or more configuration files are detected.  If the
-    pywin32 extensions are not installed, Mercurial will only look for
-    site-wide configuration in ``C:\Mercurial\Mercurial.ini``.
+    order until one or more configuration files are detected.
 
 Syntax
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