WIP: Security Enclave Development Process

Why is this change being made?

This MR documents at a high level the process for developing for the Security Enclave.

It ties together the relationships among the GitLab hosted projects and groups used for administration that is more discoverable than the respective project READMEs.

cc @kyletsmith @pharrison @jdsalaro

@gitlab-com/gl-security/automation for visibility.

Does this MR meet the acceptance criteria?

Conformity

• Added description to this MR explaining the reasons for the proposed change, per say-why-not-just-what