Fix making of "sources.html"

Uses same template as synopsis, maybe this shoudl be generalised a bit

doc/gfdoc/Makefile

@@ -0,0 +1,17 @@
+TMP=tmp.html
+TEMPLATE=../synopsis/template.html
+ROOT=../..
+
+sources.html: sources.txt $(TEMPLATE)
+	txt2tags --target=html --no-headers --quiet --toc --outfile=$@ --infile=$<
+	pandoc \
+		--from=html \
+		--to=html5 \
+		--standalone \
+		--template=$(TEMPLATE) \
+		--metadata='title:"More modules in the GF Resource Grammar Library"' \
+		--variable='rel-root:$(ROOT)/..' \
+		--output=$(TMP) \
+		$@
+	mv $(TMP) $@
+	sed -i.bak "s/<table>/<table class=\"table w-auto\">/" $@ && rm "$@.bak"