Document the new Cache API with common use cases

[shuding]

Related

• Partial matching for mutation keys: Feature request: Please add partial matching for mutation keys swr#761. Document the usage here
• Cache persistency: How can i persist data in cache but not inside Async Storage in React-Native swr#973
• Initial data related: Data is not updated with initialData swr#284, initialData has different behaviour on SSR compared to CSR swr#275
• Clear cache: Remove old cached items swr#4
• Multiple cache: Support multiple caching mechanisms swr#16

[skotchpine]

Loving the library, thanks for being conservative, having docs, etc. Go you!

@shuding is our solution here affected? vercel/swr#488

[shuding]

@skotchpine yep @huozhi is working on it in #99. You're solution will be affected, but we're going to put an example in the docs that solves the exact same problem with a more flexible way.

The old API is not ideal and we don't want people to stick with it before we have a proper solution (otherwise they have to migrate their code), that's why we didn't document it.

[huozhi]

Close this issue as cache examples are kind enough, add test solution is also resolved