[ENG-3403] Update README.md to clarify github issues policy.

[Johnetordoff]

Purpose

Clarifiy Github Issues policy.

Changes

QA Notes

Please make verification statements inspired by your code and what your code touches.

• Verify
• Verify

What are the areas of risk?

Any concerns/considerations/questions that development raised?

Documentation

Side Effects

Ticket

https://openscience.atlassian.net/browse/ENG-3403