springboot Updated CONTRIBUTING.adoc file with Maven wrapper info etc

Comment From: pivotal-issuemaster

@rdm100 Please sign the Contributor License Agreement!

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Comment From: wilkinsona

It looks like this was opened in error.

Comment From: rdm100

This was the issue I was responding to https://github.com/quick-perf/quickperf/issues/19

Comment From: wilkinsona

That's a separate repository in a separate organisation. To address that issue you'll need to make changes to https://github.com/quick-perf/quickperf/blob/master/CONTRIBUTING.md and submit a pull request to https://github.com/quick-perf/quickperf.