support creating the checksums file

Makefile

@@ -9,7 +9,7 @@ WIFI = $(wildcard *.wifi.rsc)
 MARKDOWN = $(wildcard *.md doc/*.md doc/mod/*.md)
 HTML = $(MARKDOWN:.md=.html)
 
-all: $(CAPSMAN) $(LOCAL) $(WIFI) $(HTML)
+all: $(CAPSMAN) $(LOCAL) $(WIFI) $(HTML) checksums.json
 
 %.html: %.md Makefile
 	markdown $< | sed 's/href="\([-_\./[:alnum:]]*\)\.md"/href="\1.html"/g' > $@
@@ -32,5 +32,8 @@ all: $(CAPSMAN) $(LOCAL) $(WIFI) $(HTML)
 		-e '/^# !!/,/^# !!/c # !! Do not edit this file, it is generated from template!' \
 		< $< > $@
 
+checksums.json: contrib/checksums.sh *.rsc */*.rsc
+	contrib/checksums.sh
+
 clean:
-	rm -f $(HTML)
+	rm -f $(HTML) checksums.json