make flipped version of rules

The booklet.pdf file needs flipped on the short side of the paper for it
to print properly within other books.  The booklet.pdf file can remain
in landscape mode - it'll print fine on its own when flipped on the long
edge.

.gitlab-ci.yml

@@ -11,6 +11,4 @@ build:
     - if: $CI_COMMIT_BRANCH == "run"
   artifacts:
     paths:
-      - docs.pdf
-      - booklet.pdf
-      - resources.pdf
+      - "*.pdf"

Makefile

@@ -26,10 +26,18 @@ resources.pdf: HANDOUTS STYLE_FILES | $(DROSS)
 	$(RUN) resources.tex
 	$(CP) $(DROSS)/resources.pdf resources.pdf
 
-booklet.pdf: STYLE_FILES HANDOUTS | $(DROSS)
+booklet.pdf: | STYLE_FILES HANDOUTS $(DROSS)
 	$(RUN) booklet.tex
 	$(RUN) booklet.tex
-	@pdfjam --angle 90 $(DROSS)/booklet.pdf --no-landscape --outfile $@
+	$(CP) $(DROSS)/booklet.pdf booklet.pdf
+
+/tmp/p_1.pdf: booklet.pdf
+	pdfjam --angle '90' $< 1 --outfile $@
+
+/tmp/p_2.pdf: booklet.pdf
+	pdfjam --angle '-90' $< 2 --outfile $@
+rules.pdf: /tmp/p_1.pdf /tmp/p_2.pdf
+	pdfunite $^ $@
 
 .PHONY: all clean
 all: docs.pdf booklet.pdf resources.pdf $(DROSS)/test.pdf