New Makefile; includes ../paper-letter/Makefile and sets PAPER=a4.
diff --git a/Doc/paper-a4/Makefile b/Doc/paper-a4/Makefile
new file mode 100644
index 0000000..f6d9de8
--- /dev/null
+++ b/Doc/paper-a4/Makefile
@@ -0,0 +1,2 @@
+include ../paper-letter/Makefile
+PAPER=a4