Create SECURITY.md and link to security policy
Created by: christinaforney
GitHub guidelines: https://help.github.com/en/articles/adding-a-security-policy-to-your-repository
Related: #5212 and #5217
Created by: christinaforney
GitHub guidelines: https://help.github.com/en/articles/adding-a-security-policy-to-your-repository
Related: #5212 and #5217