Add cached crate mdbook-linkcheck

[huangjj27]

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• [x] Is this related to the actions-rs Actions? If not, use GitHub Community forum to ask questions about Actions in a whole: https://github.community
• [x] Does this crate helps with the Rust CI?
• [ ] Is it popular enough to be used by many users?

Crate

crates.io: https://crates.io/crates/mdbook-linkcheck repository: https://github.com/Michael-F-Bryan/mdbook-linkcheck

Motivation

I was translating the async book and publish it with my own ci using actions-rs. However, each time it builds, actions-rs re-install mdbook-linkcheck without cache, whick takes about 5 min to pass the CI. With this crate cached, the CI will be made less than 20s.