doctests fail when client is embedded into the generated crate

When using cargo progenitor with --include-client true, the generated crate embeds progenitor_client as a local module rather than as an external crate dependency. This causes cargo test --doc to fail because the doctest harness can't resolve use progenitor_client::...; there's no external crate by that name, only a local module.

The workaround we're using is manually appending [lib]\ndoctest = false to the generated Cargo.toml after generation, which does the job for our use case. We can continue doing that but I was wondering if this is something you're willing to have fixed.

One possible fix could be to have cargo-progenitor emit that section automatically when --include-client true is used, since it already has that information when constructing the Cargo.toml. Not sure if there are reasons not to do this or a better approach. Would love to send a PR if the direction makes sense!

Start at the cargo-progenitor generation path that handles --include-client true and constructs the generated Cargo.toml. Reproduce the failure with cargo test --doc, then verify that generated crates no longer fail to resolve progenitor_client when the embedded client is used.