Add Cargo package metadata for publishing to crates.io

[nukopy]

Why

On GitHub Actions workflow "Release", the following error occurs on publishing to crates.io:

Run cargo publish --token ***
    Updating crates.io index
warning: manifest has no description, license, license-file, documentation, homepage or repository.
See https://doc.rust-lang.org/cargo/reference/manifest.html#package-metadata for more info.
   Packaging knsh v0.0.2 (/home/runner/work/knsh/knsh)
   Verifying knsh v0.0.2 (/home/runner/work/knsh/knsh)
   Compiling knsh v0.0.2 (/home/runner/work/knsh/knsh/target/package/knsh-0.0.2)
    Finished dev [unoptimized + debuginfo] target(s) in 0.81s
    Packaged 13 files, 8.6KiB (3.8KiB compressed)
   Uploading knsh v0.0.2 (/home/runner/work/knsh/knsh)
error: failed to publish to registry at https://crates.io

Caused by:
  the remote server responded with an error: missing or empty metadata fields: description, license. Please see https://doc.rust-lang.org/cargo/reference/manifest.html for more information on configuring these fields
Error: Process completed with exit code 101.

The error message referred to the Cargo documentation, which indicated that the following metadata in the Cargo.toml file is required for publishing to crates.io:

• license or license-file
• description
• homepage
• documentation
• repository
• readme

What

• Add Cargo package metadata to Cargo.toml