makefile: auto-format xml docs outside of the doc subdir

Changed files
+1 -1
nixos
doc
manual
+1 -1
nixos/doc/manual/Makefile
···
.PHONY: format
format:
-
find . -iname '*.xml' -type f -print0 | xargs -0 -I{} -n1 \
+
find ../../ -iname '*.xml' -type f -print0 | xargs -0 -I{} -n1 \
xmlformat --config-file "../xmlformat.conf" -i {}
.PHONY: fix-misc-xml