Move Doxygen docs to subdirectory (#16561)

util/generate_internal_docs.sh

@@ -1,31 +0,0 @@
-#!/usr/bin/env bash
-
-set -x
-
-if ! doxygen -v 2>&1 > /dev/null; then
-	echo "doxygen not found! Please install it!"
-	exit 1
-elif ! moxygen -V 2>&1 > /dev/null; then
-	echo -n "moxygen not found! Would you like to install it? [y/n] "
-	read ANSWER
-	case $ANSWER in
-		y|Y|yes|YES|Yes)
-			npm install -g moxygen
-		;;
-		*)
-			exit 1
-		;;
-	esac
-fi
-
-if [ ! -e Doxyfile ]; then
-	echo "Error: You must run this from the top-level qmk_firmware directory!"
-	exit 1
-fi
-
-# Generate the doxygen XML files
-rm -rf doxygen
-doxygen Doxyfile
-
-# Generate the moxygen Markdown files
-moxygen -a -g -o docs/internals_%s.md doxygen/xml