userguide: Generate userguide.tex to include \tightlist macro

Allow xelatex to build userguide.pdf without errors.

pandoc injects \tightlist macros into its output files which cause
xelatex to choke. By processing the hand-rolled userguide.tex with
pandoc the definition is injected and xelatex can build the PDF.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/Makefile b/Makefile
index 82ec1c3..c00b79c 100644
--- a/Makefile
+++ b/Makefile
@@ -6,9 +6,12 @@
 
 .PHONY: all clean
 
-userguide.pdf: userguide/userguide.tex
+userguide.pdf: userguide.tex
 	$(tex) $^
 
+userguide.tex: userguide/userguide.tex
+	pandoc -f latex -t latex -s -o $@ $^
+
 userguide/userguide.tex: rest-api.tex host-management.tex console.tex code-update.tex
 
 %.tex: %.md