Add esp32 example

examples/esp32/Makefile

@@ -0,0 +1,10 @@
+THISDIR = $(realpath $(CURDIR))
+ROOTDIR = $(realpath $(CURDIR)/../..)
+
+all: example
+
+example:
+	docker run --rm -v $(ROOTDIR):$(ROOTDIR) -w $(THISDIR) espressif/idf idf.py build
+
+clean:
+	rm -rf $(PROG) *.o *.dSYM *.gcov *.gcno *.gcda *.obj *.exe *.ilk *.pdb mongoose mongoose_* mongoose.* build sdkconfig