Formatting SD guide (Windows) (#1760)

* add formatting-sd-(windows)

Unfinished page, needs a few more updates.

* formatting-sd-(windows): volume label should be blank

* formatting-sd-(windows): add warning after choosing drive letter

* formatting-sd-(windows): allow any volume label

* update format link

* formatting-sd-(windows): use 32768 allocation unit size for 64GB

_pages/en_US/formatting-sd-(windows).txt

@@ -0,0 +1,46 @@
+---
+title: "Formatting SD (Windows)"
+---
+
+{% include toc title="Table of Contents" %}
+
+### Required Reading
+
+This is an add-on section for formatting an SD card to work with the 3DS.
+
+If the 3DS already recognizes the SD card, this guide is not required.
+
+This page is for Windows users only. If you are not on Windows, check out the [Formatting SD (Linux)](formatting-sd-(linux)) or [Formatting SD (Mac)](formatting-sd-(mac)) pages.
+
+### What You Need
+
+* The latest version of [guiformat](http://ridgecrop.co.uk/index.htm?guiformat.htm)
+
+### Instructions
+
+1. Insert your SD card into your computer
+1. If the SD card has any files and folders on it, copy everything to a folder on your computer
+1. Run `guiformat.exe`
+1. Select your SD card's drive letter for "Drive"
+
+	Make sure you choose the correct drive letter, otherwise you might accidentally erase the wrong drive!
+	{: .notice--danger}
+
+1. Select a size for "Allocation unit size"
+  + If the SD card is 64GB or below, choose 32768
+  * If the SD card is above 64GB, choose 65536
+1. Enter anything for "Volume label"
+1. Ensure that "Quick Format" is selected
+1. Click "Start"
+1. Click "OK"
+1. Wait for the format to finish
+1. Click "Close"
+1. If the SD card had any files and folders on it before the format, copy everything back from your computer
+
+### Common Errors
+
+* Failed to open device: GetLastError()=32
+  + Close everything that may be using the SD card, such as any File Explorer windows.
+
+### Return to [Get Started](get-started)
+{: .notice--primary}