added code of conduct to project

[jivthesh]

Thank you for submitting a contribution to Apache Geode.

In order to streamline the review of the contribution we ask you
to ensure the following steps have been taken:

For all changes:

• Is there a JIRA ticket associated with this PR? Is it referenced in the commit message?

• Has your PR been rebased against the latest commit within the target branch (typically develop)?

• Is your initial contribution a single, squashed commit?

• Does gradlew build run cleanly?

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Note:

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submit an update to your PR as soon as possible. If you need help, please send an
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[metatype]

Thanks for this submission! I appended the Geode CoC to your PR. Hope that's ok :-)

[jivthesh]

@metatype okay

[jivthesh]

@metatype should i wnat to make any changes