:wrench: Simplify makefile with a generic recipe

One recipe to rule them all.

makefile

@@ -38,25 +38,14 @@ dist: $(DIST_DIR)
 
 $(DIST_DIR): $(DIST_FILES)
 
-$(DIST_DIR)/include/%: src/include/%
-	mkdir --parents $(dir $@)
-	cp $< $@
-
-$(DIST_DIR)/download/%: src/download/%
-	mkdir --parents $(dir $@)
-	cp $< $@
-
 $(DIST_DIR)/%.html: src/%.gen.html
 	mkdir --parents $(dir $@)
 	cp $< $@
 
-$(DIST_DIR)/%.png: src/%.png
+$(DIST_DIR)/%: src/%
 	mkdir --parents $(dir $@)
 	cp $< $@
 
-$(DIST_DIR)/favicon.ico: src/favicon.ico
-	cp $< $@
-
 .PHONY: clean
 clean:
 	rm -f $(GEN_FILES)