Add simple ocf usage example

Signed-off-by: Robert Baldyga <robert.baldyga@intel.com>

example/simple/Makefile

@@ -0,0 +1,37 @@
+#
+# Copyright(c) 2019 Intel Corporation
+# SPDX-License-Identifier: BSD-3-Clause-Clear
+#
+
+OCFDIR=../../
+SRCDIR=src/
+INCDIR=include/
+
+SRC=$(shell find ${SRCDIR} -name \*.c)
+OBJS = $(patsubst %.c, %.o, $(SRC))
+PROGRAM=simple
+
+CC = gcc
+CFLAGS = -g -Wall -I${INCDIR} -I${SRCDIR}/ocf/env/
+LDFLAGS = -lm -lz -pthread
+
+all: sync
+	$(MAKE) $(PROGRAM)
+
+$(PROGRAM): $(OBJS)
+	$(CC) $(LDFLAGS) -o $@ $^
+
+sync:
+	@$(MAKE) -C ${OCFDIR} inc O=$(PWD)
+	@$(MAKE) -C ${OCFDIR} src O=$(PWD)
+	@$(MAKE) -C ${OCFDIR} env O=$(PWD) ENV=posix
+
+clean:
+	@rm -rf $(PROGRAM) $(OBJS)
+
+distclean:
+	@rm -rf $(PROGRAM) $(OBJS)
+	@rm -rf src/ocf
+	@rm -rf include/ocf
+
+.PHONY: all clean