Create SECURITY.md

[ragwell]

Description

A few sentences describing the overall goals of the pull request's commits.

Issues This PR Fixes

Fixes #NNNN
Fixes #NNNN

Related PRs

List related PRs against other branches e.g. for backporting features/bugfixes
to previous release branches:

Repo/Branch	PR
some_other_PR	link

Todos

• Tested and working on development environment
• Unit tests (if appropriate)
• Added/Updated all related documentation. Add link if different from this PR
• DevOps Support needed e.g. create Runscope API test if new endpoint added or
  update deployment docs. Create a ticket and add link

Deployment Notes

Notes about how to deploy this work. For example, running a migration against the production DB.

How to QA

Outline the steps to test or reproduce the PR here.

Impacted Areas in Application

List general components of the application that this PR will affect:

• Scale
• Performance
• Security etc.