Update caching docs

[mandiwise]

Description

This PR expands on the existing caching content for the Learn docs so that it addresses broader performance topics. Key changes include:

• New content on using GET to facilitate caching, the N+1 problem, performance monitoring, and more
• Page has been renamed "Performance" (with redirect from old route)

@benjie @jorydotcom

[vercel]

@mandiwise is attempting to deploy a commit to the The GraphQL Foundation Team on Vercel.

A member of the Team first needs to authorize it.

[saihaj]

let's keep a dedicated caching page on that page we can talk about different caching techniques used within community: Document Caching, Response Caching, Partial Query Caching.

We can talk about performance and add more things to that page. The performace page can link to the caching page. Performance is a broader topic, we can even take things like Trusted documents and refer in performance section.