separate-debug-symbols in Cargo.toml is ignored

[punkeel]

### `[package.metadata.deb]` options

Everything is optional:

- **name**:  ...
- ...
 - **separate-debug-symbols**: whether to keep debug symbols, but strip them from executables and save them in separate files (default `false`).
 - **preserve-symlinks**: ...

The README mentions a separate-debug-symbols option that can be set in Cargo.toml, but this option seems to be ignored. Looking at the source of cargo-deb, I'm not sure this was ever implemented.

Should it be removed from README, or support for this be added?

[kornelski]

It'd be great if you could add the support.