[secrets] Add a `secrets` directory encrypted with `git-crypt` + README

This adds an encrypted `secrets` directory for low-security secrets, such as configuration keys for the client. See the README

[secrets] Add a `secrets` directory encrypted with `git-crypt` + README

This adds an encrypted `secrets` directory for low-security secrets, such as configuration keys for the client. See the README for more details.

Test plan: Added a test file with some placeholder text to verify that it is encrypted on GitHub.

show more ...