write man; fix man build

Makefile

@@ -29,8 +29,10 @@ docs:
 	make $(strip $(DOCS))
 
 build/man/%: docs/%.md build/man/ docs/
-	pandoc --from markdown --to man \
-		$< $@
+	pandoc --to man \
+		--standalone \
+		--output $@ \
+		$<
 
 %/:
 	@mkdir -p $@