PLAT-1342 Add Contribution Guidelines to Platform Open Source README files

PLAT-1342 Add Contribution Guidelines to Platform Open Source README files

https://newrelic.atlassian.net/browse/PLAT-1342
Merge pull request #3 from newrelic-platform/bdelahunty/PLAT-1342

PLAT-1342 Add Contribution Guidelines to Platform Open Source README files