fix: include memory layout files in metapac package

[andelf]

This fixes the generated ch32-metapac package include list for the new runtime memory layout files introduced by Rich Memory Layout (#36).

cargo publish --dry-run --features ch32v003f4u6 currently fails after copying README/LICENSE because the crate tarball excludes src/chips/**/memory_x/**, so build.rs cannot read memory_x/_default from the packaged crate. README and license files are also referenced by the manifest/publish metadata, so include them explicitly.

@aq1018 FYI, this is the packaging follow-up for the memory layout work. After this lands, we plan to regenerate/push ch32-metapac and publish ch32-metapac 0.1.0 to crates.io.

Verification:

./d gen
cd build/ch32-metapac
cp ../../README.md .
cp ../../LICENSE* .
cargo publish --dry-run --features ch32v003f4u6

The dry run packages 803 files and verifies ch32-metapac v0.1.0 successfully.