Fix typos and improve clarity in build-cache.md

[ncsokas]

This pull request updates the labs/build-cache.md file to improve clarity, correct terminology, and enhance the guidance on caching and artifact usage in GitHub Actions workflows. The most important changes include fixing typos, adding a comparison of caching vs. artifacts, and providing a detailed example workflow for caching and artifact management.

• Provided a detailed example of a GitHub Actions workflow for caching Gradle dependencies, managing Docker layer caching, and using artifacts for cross-job communication. This includes a fully fleshed-out YAML example with caching and artifact upload/download steps.
• Recommended using docker/build-push-action for efficient Docker layer caching and suggested changing workflow triggers to workflow_dispatch to avoid unnecessary runs.

[amrutashety]

LGTM