Adding a dummy, top-level secrets.json file using `git-secret`. It might be nice
to have a mono-secrets file in json because then I can use it with `jq` like:
```shell
$ jq '.secret' --join-output < ~/briefcase/secrets.json
```
This morning I'm attempting to secure my monorepo. How?
- `git secret`: DONE: To version-control sensitive data
- `git secrets`: TODO: Lint code for sensitive data
I will probably update the CI to call `git secrets --scan` or some similar
command to fail when that exists non-zero. I have much to learn, but doing is
the best way to learn it.