Add Zadig 101 to docs (#6585)

* Add Zadig 101 to docs

* Add USBasp bootloader name

* Add links to the page

* Note the usual VIDs and PIDs for the bootloaders

* Add "List All Devices" note, just in case

* Talk about keyboard-specific bootloader procedures

* Send users to the new page in "Unknown Device for DFU Bootloader" section

* Halfkay bootloaders are also an exception here

3 files changed, 46 insertions, 6 deletions

diff --git a/docs/_summary.md b/docs/_summary.md
index 56184f44de..95286ff46c 100644
--- a/docs/_summary.md
+++ b/docs/_summary.md
@@ -18,6 +18,7 @@
   * [Build/Compile QMK](faq_build.md)
   * [Debugging/Troubleshooting QMK](faq_debug.md)
   * [Keymap](faq_keymap.md)
+  * [Driver Installation with Zadig](driver_installation_zadig.md)
 
 * Detailed Guides
   * [Install Build Tools](getting_started_build_tools.md)
diff --git a/docs/driver_installation_zadig.md b/docs/driver_installation_zadig.md
new file mode 100644
index 0000000000..ccee7008eb
--- /dev/null
+++ b/docs/driver_installation_zadig.md
@@ -0,0 +1,42 @@
+# Bootloader Driver Installation with Zadig
+
+QMK presents itself to the host as a regular HID keyboard device, and as such requires no special drivers. However, in order to flash your keyboard on Windows, the bootloader device that appears when you reset the board often *does*.
+
+There are two notable exceptions: the Caterina bootloader, usually seen on Pro Micros, and the Halfkay bootloader shipped with PJRC Teensys, appear as a serial port and a generic HID device respectively, and so do not require a driver.
+
+We recommend the use of the [Zadig](https://zadig.akeo.ie/) utility. If you have set up the development environment with Msys2 or WSL, the `qmk_install.sh` script will have asked if you want it to install the drivers for you.
+
+## Installation
+
+Place your keyboard into the bootloader mode, either by hitting the `RESET` keycode (which may be on a different layer), or by pressing the reset switch usually located on the underside of the board. If your keyboard has neither, try holding Escape, or Space+`B`, as you plug it in (see the [Bootmagic](feature_bootmagic.md) docs for more details).
+Some keyboards may have specific instructions for entering the bootloader, for example the [Bootmagic Lite](feature_bootmagic.md#bootmagic-lite) key (Escape) might be on a different key, such as Left Control. Refer to the board's README if you are unsure.
+
+Zadig will automatically detect the bootloader device. You may sometimes need to check **Options -> List All Devices**.
+ - For keyboards with Atmel AVR MCUs, the bootloader will be named something similar to `ATm32U4DFU`, and have a Vendor ID of `03EB`.
+ - USBasp bootloaders will appear as `USBasp`, with a VID/PID of `16C0:05DC`.
+ - AVR keyboards flashed with the QMK-DFU bootloader will be named `<keyboard name> Bootloader` and will also have the VID `03EB`.
+ - For most ARM keyboards, it will be called `STM32 BOOTLOADER`, and have a VID/PID of `0483:DF11`.
+
+!> If Zadig lists one or more devices with the `HidUsb` driver, your keyboard is probably not in bootloader mode. The arrow will be colored orange and you will be asked to confirm modifying a system driver. **Do not** proceed if this is the case!
+
+If the arrow appears green, select the driver, and click **Install Driver**. The `libusb-win32` driver will usually work for AVR, and `WinUSB` for ARM, but if you still cannot flash the board, try installing a different driver from the list.
+
+![Zadig with a bootloader driver correctly installed](https://i.imgur.com/b8VgXzx.png)
+
+Finally, unplug and replug the keyboard to make sure the new driver has been loaded. If you are using the QMK Toolbox to flash, exit and restart it too, as it can sometimes fail to recognize the driver change.
+
+## Recovering from Installation to Wrong Device
+
+If you find that you can no longer type with the keyboard, you may have installed the driver onto the keyboard itself instead of the bootloader. You can easily confirm this in Zadig - a healthy keyboard has the `HidUsb` driver installed on all of its interfaces:
+
+![A healthy keyboard as seen by Zadig](https://i.imgur.com/Hx0E5kC.png)
+
+Open the Device Manager and look for a device that looks like your keyboard.
+
+![The board with the wrong driver installed, in Device Manager](https://i.imgur.com/L3wvX8f.png)
+
+Right-click it and hit **Uninstall device**. Make sure to tick **Delete the driver software for this device** first.
+
+![The Device Uninstall dialog, with the "delete driver" checkbox ticked](https://i.imgur.com/aEs2RuA.png)
+
+Click **Action -> Scan for hardware changes**. At this point, you should be able to type again. Double check in Zadig that the keyboard device(s) are using the `HidUsb` driver. If so, you're all done, and your board should be functional again!
diff --git a/docs/faq_build.md b/docs/faq_build.md
index 3fe358edaf..f11cb76aa2 100644
--- a/docs/faq_build.md
+++ b/docs/faq_build.md
@@ -75,14 +75,11 @@ Pro Micro (Atmega32u4), make sure to include `CONFIG_USB_ACM=y`. Other devices m
 
 ## Unknown Device for DFU Bootloader
 
-Issues encountered when flashing keyboards on Windows are most often due to having the wrong drivers installed for the bootloader. 
+Issues encountered when flashing keyboards on Windows are most often due to having the wrong drivers installed for the bootloader, or none at all.
 
-Re-running the installation script for MSYS2 may help (eg run `util/qmk_install.sh` from MSYS2/WSL) or reinstalling the QMK Toolbox may fix the issue. Alternatively, you can download and run the [`qmk_driver_installer`](https://github.com/qmk/qmk_driver_installer) package.
-
-If that doesn't work, then you may need to grab the [Zadig Utility](https://zadig.akeo.ie/). Download this, and run it on the system.  Then, you will need to reset your board into bootloader mode.  After that, locate the device in question. If the device doesn't show up in the list (or nothing shows up in the list), you may need to enable the `List all devices` option in the `Options` menu.
-
-From here, you will need to know what type of controller the board is using.  You may see it listed in the Device Manager as `ATmega32U4` device (which is an AVR board), or an `STM32` device (Which is an ARM board).  For AVR boards, use `libusb-win32` for the driver. For ARM boards, use the `WinUSB` driver.  Once the correct driver type has been selected, click on the `Replace Driver` button, unplug your board, plug it back in, and reset it again.
+Re-running the QMK installation script (`./util/qmk_install.sh` from the `qmk_firmware` directory in MSYS2 or WSL) or reinstalling the QMK Toolbox may fix the issue. Alternatively, you can download and run the [`qmk_driver_installer`](https://github.com/qmk/qmk_driver_installer) package manually.
 
+If that doesn't work, then you may need to download and run Zadig. See [Bootloader Driver Installation with Zadig](driver_installation_zadig.md) for more detailed information.
 
 ## WINAVR is Obsolete
 It is no longer recommended and may cause some problem.