chore(package): publish xtask-kit package name

[AprilNEA]

Summary

• publish compatibility release xtask@0.1.4
• publish new non-colliding package name xtask-kit@0.1.4
• update package metadata and examples for the xtask-kit crate import path
• document that future releases should publish both package names with the same version

Published

• https://crates.io/crates/xtask/0.1.4
• https://crates.io/crates/xtask-kit/0.1.4

Verification

• cargo fmt --check
• cargo check --all-features
• cargo publish --dry-run --all-features --allow-dirty for both package names