Eallred google patch 1 (#1909)

* Update README.md

fixed broken link to K8 / Knative installation instructions

* Update README.md

Arun Gupta blog is not responding with content - added Arun Gupta github link for this instead.

Author: eallred-google

docs/serving/samples/hello-world/helloworld-java-spark/README.md

@@ -11,7 +11,7 @@ testing.
 ## Prerequisites
 
 - A Kubernetes cluster with Knative installed and DNS configured. Follow the
-  [installation instructions](https://github.com/knative/docs/blob/master/install/README.md)
+  [installation instructions](../../../../install/README.md)
   if you need to create one.
 - [Docker](https://www.docker.com) installed and running on your local machine,
   and a Docker Hub account configured (we'll use it for a container registry).
@@ -48,7 +48,7 @@ recreate the source files from this folder.
    block below into it. For detailed instructions on dockerizing a Spark Java
    app, see [Spark with Docker](http://sparkjava.com/tutorials/docker). For
    additional information on multi-stage docker builds for Java see
-   [Creating Smaller Java Image using Docker Multi-stage Build](http://blog.arungupta.me/smaller-java-image-docker-multi-stage-build/).
+   [Creating Smaller Java Image using Docker Multi-stage Build](https://github.com/arun-gupta/docker-java-multistage).
 
    ```docker
     # Use the official maven/Java 8 image to create a build artifact.