fix(generate-registry): format description of cargo packages

[suzuki-shunsuke]

aqua gr crates.io/dd-rust-license-tool

Before:

packages:
  - name: crates.io/dd-rust-license-tool
    type: cargo
    repo_owner: DataDog
    repo_name: rust-license-tool
    description: A tool for creating the `LICENSE-3rdparty.csv` file for DataDog open-source Rust projects.
    crate: dd-rust-license-tool

After:

packages:
  - name: crates.io/dd-rust-license-tool
    type: cargo
    repo_owner: DataDog
    repo_name: rust-license-tool
    description: A tool for creating the `LICENSE-3rdparty.csv` file for DataDog open-source Rust projects
    crate: dd-rust-license-tool