Simplify Windows install instructions (fixes #3207)

Pinging @ndmitchell

Author: snoyberg

doc/install_and_upgrade.md

@@ -24,42 +24,26 @@ find links that always point to the latest bindists
 
 ## Windows
 
-*Note*: Due to specific Windows limitations,
- [some temporary workarounds](https://www.fpcomplete.com/blog/2015/08/stack-ghc-windows)
- may be required. It is strongly advised to set your `STACK_ROOT` environment
- variable similarly to your root (e.g., `set STACK_ROOT=c:\stack_root`) *before*
- running `stack`.
-
-*Note:* while generally 32-bit GHC is better tested on Windows, there are
-reports that recent versions of Windows only work with the 64-bit version of
-Stack (see
-[issue #393](https://github.com/commercialhaskell/stack/issues/393)).
-
-### Installer
-
 We recommend installing to the default location with these installers, as that
 will make `stack install` and `stack upgrade` work correctly out of the box.
 
-  * [Windows 32-bit Installer](https://www.stackage.org/stack/windows-i386-installer)
   * [Windows 64-bit Installer](https://www.stackage.org/stack/windows-x86_64-installer)
+  * [Windows 32-bit Installer](https://www.stackage.org/stack/windows-i386-installer)
+
+If in doubt: you should prefer the 64-bit installer.
 
 ### Manual download
 
 * Download the latest release:
 
-    * [Windows 32-bit](https://www.stackage.org/stack/windows-i386)
     * [Windows 64-bit](https://www.stackage.org/stack/windows-x86_64)
+    * [Windows 32-bit](https://www.stackage.org/stack/windows-i386)
 
 * Unpack the archive and place `stack.exe` somewhere on your `%PATH%` (see
   [Path section below](#path)) and you can then run `stack` on the command line.
 
 * Now you can run `stack` from the terminal.
 
-NOTE: These executables have been built and tested on a Windows 7, 8.1, and 10
-64-bit machines. They should run on older Windows installs as well, but have not
-been tested. If you do test, please edit and update this page to indicate as
-such.
-
 ## macOS
 
 We generally test on the current version of macOS, but Stack is known to work