GNUmakefile: add some documentation for the INDICES variable.

diff --git a/GNUmakefile b/GNUmakefile
index 49cca6a6cc4aff1a4acee75c6d8017e25ce61bb7..1f65dd9b892a388624b3a576076cc70f2c391afc 100644 (file)
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -36,6 +36,12 @@ MJOTEX += mjo-theorem-star.tex mjo-topology.tex mjo.bst
 SAGE_LISTING_SRCS = $(wildcard sage_listings/*.listing)
 SAGE_LISTING_DSTS = $(patsubst %.listing,%.py,$(SAGE_LISTING_SRCS))
 
+# A space-separated list of indices (just their names). Usually you'll
+# have just one, and it will be named the same thing as your document,
+# because that's what the makeidx package does.
+#
+# Leave commented if you don't use an index.
+#
 INDICES = $(PN)
 
 # Use kpsewhich (from the kpathsea suite) to find the absolute paths