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

[michaelin]

Added initial findings. More may come when I've run the exercise myself.

[michaelin]

Suggested change

	To use cache at the consecutive jobs, the same code (from above example) has to be added as a step to each job.
	To use the cache in subsequent jobs, a step with the same cache configuration has to be added to each job.

The change from "consecutive" to "subsequent" is most important. The rest of the suggestion just my preference.

[michaelin]

Suggested change

	## Recap: Caching vs. Artifacts
	`actions/cache`: Its purpose is to speed up future workflow runs by saving and reusing files that don't change often, like third-party dependencies (~/.gradle/caches). It is not designed to pass files between jobs in the same run.
	## Recap: Caching vs. Artifacts
	`actions/cache`: Its purpose is to speed up future workflow runs by saving and reusing files that don't change often, like third-party dependencies (~/.gradle/caches). It is not designed to pass files between jobs in the same run.

Nitpick: There should be a newline after headings

[michaelin]

I'm a bit iffy on terminology here. I would expect it to be called a "GitHub Actions workflow file"? Or here, maybe just a "workflow file", since we're already in context of GitHub Actions. The more we sprinkle GitHub Actions around, the more it sounds like marketing material for GitHub.

Suggested change

	1. Create a new GitHub Actions file under `./github/workflows/caching.yaml` with exact copy of the pipeline from [exercise 7](../trainer/.github/workflows/caching.yaml) .
	1. Create a new workflow file under `./github/workflows/caching.yaml` with an exact copy of the pipeline from [exercise 7](../trainer/.github/workflows/caching.yaml) .