[Docs] Update ISP Guide (qmk#9748)

* [Doc] Update ISP Guide

Correct the fuses for Caterina, and make the `:production` command more obvious.

* fix casing before fauxpark catches it

docs/isp_flashing_guide.md

@@ -141,7 +141,9 @@ To do this manually:
 
 ?> It's possible to use other bootloaders here in the same way, but __you need a bootloader__, otherwise you'll have to use ISP again to write new firmware to your keyboard.
 
-To do this the easy way, you can flash the board using the `:production` target when compiling.  This compiles the firmware, then compiles the QMK DFU bootloader, and then creates a combined image.  Once this is done, you'll see three files: 
+#### Create QMK DFU Bootloader and Production images
+
+You can create the firmware, the QMK DFU Bootloader and the production firmware images for the board using the `:production` target when compiling.  Once this is done, you'll see three files: 
 * `<keyboard>_<keymap>.hex`
 * `<keyboard>_<keymap>_bootloader.hex`
 * `<keyboard>_<keymap>_production.hex`
@@ -236,12 +238,12 @@ For Caterina on the `atmega32u4`, these are the fuse settings that you want:
 | Fuse     | Setting|
 |----------|--------|
 | Low      | `0xFF` |
-| High     | `0xD9` |
-| Extended | `0xC3` |
+| High     | `0xD8` |
+| Extended | `0xCB` |
 
-To set this add `-U lfuse:w:0xFF:m -U hfuse:w:0xD8:m -U efuse:w:0xC3:m` to your command.  So the final command should look something like: 
+To set this add `-U lfuse:w:0xFF:m -U hfuse:w:0xD8:m -U efuse:w:0xCB:m` to your command.  So the final command should look something like: 
 
-    avrdude -c avrisp -P COM3 -p atmega32u4 -U flash:w:main.hex:i -U lfuse:w:0xFF:m -U hfuse:w:0xD8:m -U efuse:w:0xC3:m
+    avrdude -c avrisp -P COM3 -p atmega32u4 -U flash:w:main.hex:i -U lfuse:w:0xFF:m -U hfuse:w:0xD8:m -U efuse:w:0xCB:m
 
 
 If you are using a different controller or want different configuration, you can use [this AVR Fuse Calculator](http://www.engbedded.com/fusecalc/) to find a better value for you.