Change the quick guide with Spark Exetension use cases

[paryoja]

What is the context for this pull request?

• Tracking Issue: #503
• Dependencies: #504

What changes were proposed in this pull request?

According to the use case of Spark Extension, guide is update accordingly.

Does this PR introduce any user-facing change?

No. User-facing changes will be done by #504 .

How was this patch tested?

Tested manually.

[sezruby]

You can check the result after setting "Pages" branch/directory in your repository. Setting -> Pages -> setting source as the branch & "/docs", then you can see your change in https://paryoja.github.io/hyperspace/

Could you set the page for reviewers? Thanks!