Add simple example built with CMake

examples/cmake_simple/README.txt

@@ -0,0 +1,25 @@
+Nanopb example "simple" using CMake
+=======================
+
+This example is the same as the simple nanopb example but built using CMake.
+
+Example usage
+-------------
+
+On Linux, create a build directory and then call cmake:
+
+    nanopb/examples/cmake_simple$ mkdir build
+    nanopb/examples/cmake_simple$ cd build/
+    nanopb/examples/cmake_simple/build$ cmake ..
+    nanopb/examples/cmake_simple/build$ make
+
+After that, you can run it with the command: ./simple
+
+#On other platforms, you first have to compile the protocol definition using
+#the following command::
+#
+#  ../../generator-bin/protoc --nanopb_out=. simple.proto
+#
+#After that, add the following four files to your project and compile:
+#
+#  simple.c  simple.pb.c  pb_encode.c  pb_decode.c