add example function image Dockerfile (#144)

* add example functions

* fix README.md

Author: freeznet

images/README.md

@@ -152,3 +152,7 @@ When you use Function Mesh with self build images, you need to define the execut
 ## Scripts
 
 `build.sh` is a bash script used to build base, Java, Python, and Golang runner locally.
+
+## Samples
+
+`function-samples` has a sample `Dockerfile` that copies `/pulsar/examples` from `pulsar-all` into `java-runner`, which can be used to test Function Mesh.

images/function-samples/Dockerfile

@@ -0,0 +1,4 @@
+ARG PULSAR_IMAGE_TAG
+FROM streamnative/pulsar-all:${PULSAR_IMAGE_TAG} as pulsar-all
+FROM streamnative/pulsar-functions-java-runner:${PULSAR_IMAGE_TAG}
+COPY --from=pulsar-all --chown=pulsar:0 /pulsar/examples /pulsar/examples