Allow root path ('/')

The schema is currently using this pattern for paths (both within "paths" and "tags"): `^/.*[^\/]$`

This ensures:
- The path starts with a slash
- The path does not end with a slash (I agree this is a best practice but I'm not sure it should be strictly enforced)

The problem is that it doesn't allow a set of operations to exist at the root path: `/`

I've changed the regex to `"^\/$|^\/.*[^\/]$"` to allow '/' (but not `/foo/`) and added an example that uses the root path.