config-settings.html depends on generate-settings.sh

If the script changes, the output could change, so we need to regenerate
config-settings.html.

doc/Makefile.am

@@ -5,6 +5,6 @@ htmldocdir = $(prefix)/share/docsis
 EXTRA_DIST=generate-settings.sh index.html config-format.html
 CLEANFILES=config-settings.html
 
-config-settings.html: ../src/docsis_symtable.h
+config-settings.html: generate-settings.sh ../src/docsis_symtable.h
 	/bin/sh -e $(srcdir)/generate-settings.sh \
 		config-settings.html $(VERSION)