Fix #11834. Correct site-packages paths.

Patch by Bryce Verdier.

Author: briancurtin

Doc/install/index.rst

@@ -241,7 +241,7 @@ is pure Python or contains extensions ("non-pure"):
 +-----------------+-----------------------------------------------------+--------------------------------------------------+-------+
 | Unix (non-pure) | :file:`{exec-prefix}/lib/python{X.Y}/site-packages` | :file:`/usr/local/lib/python{X.Y}/site-packages` | \(1)  |
 +-----------------+-----------------------------------------------------+--------------------------------------------------+-------+
-| Windows         | :file:`{prefix}`                                    | :file:`C:\\Python`                               | \(2)  |
+| Windows         | :file:`{prefix}\\Lib\\site-packages`                | :file:`C:\\Python{XY}\\Lib\\site-packages`       | \(2)  |
 +-----------------+-----------------------------------------------------+--------------------------------------------------+-------+
 
 Notes: