[build] include cleanup targets in makefile usage message

1 files changed, 3 insertions, 0 deletions

diff --git a/Makefile b/Makefile
index 60dec60..17f583f 100644
--- a/Makefile
+++ b/Makefile
@@ -227,5 +227,8 @@ showtargets:
 	@echo "       ctan        package a zipball for uploading to CTAN"
 	@echo "       sign        sign zipball"
 	@echo
+	@echo "       clean       cleanup side-effects"
+	@echo "       mrproper    cleanup side-effects as well as make targets"
+	@echo
 
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