[SPARK-16312][FOLLOW-UP][STREAMING][KAFKA][DOC] Add java code snippet for Kafka 0.10 integration doc

## What changes were proposed in this pull request?

added java code snippet for Kafka 0.10 integration doc

## How was this patch tested?

SKIP_API=1 jekyll build

## Screenshot

![kafka-doc](https://cloud.githubusercontent.com/assets/15843379/19826272/bf0d8a4c-9db8-11e6-9e40-1396723df4bc.png)

Author: Liwei Lin <lwlin7@gmail.com>

Closes #15679 from lw-lin/kafka-010-examples.