[Request] Add example on how to cache across jobs.

[darkseid-is]

I will be quite helpful to add and example of how to cache across jobs. Setting same prefix-key, shared-key and key isn't working.

Thanks You.

[chrisgrounds]

Not sure if this is a bug or just something I'm missing, but I also can't get it to share the cache across jobs @Swatinem.

For example, within the same pipeline:

Job 1 produces a cache key of: "v0-rust-{shared-key}-6e4da2ef-b4e4aeb9"
Job 2 produces a cache key of: "v0-rust-{shared-key}-e3066001-b4e4aeb9"

(italics for the bit that's different, but shouldn't be as far as I can tell).

My understanding based on the documentation is that setting shared-key should be enough to ensure the cache key is the same across jobs within a pipeline build. Is that not right?