docs: add documentation for cache.batch method (#12990)

[bas0N]

docs: add documentation for cache.batch method

Fixes #12990

Adds comprehensive documentation for the cache.batch method:

• JSDoc (src/cache/core/cache.ts) - Added doc block with description, examples, and parameter docs
• Guide (docs/source/caching/cache-interaction.mdx) - New section covering usage, optimistic updates, and onWatchUpdated
• API Reference (docs/source/api/cache/InMemoryCache.mdx) - Full API docs with options table and signature

[apollo-cla]

@bas0N: Thank you for submitting a pull request! Before we can merge it, you'll need to sign the Apollo Contributor License Agreement here: https://contribute.apollographql.com/

[changeset-bot[bot]]

⚠️ No Changeset found

Latest commit: d91eab0072036ecdc66a1360f26dec9a9f22e3bd

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[pkg-pr-new[bot]]

npm i https://pkg.pr.new/apollographql/apollo-client/@apollo/client@13048

commit: 51cbcff

[phryneas]

Thank you for the contribution, let's get this into the docs! 🎉