Adding a Gitpod configuration to the project.

[WadeWaldron]

Description

Added a Gitpod configuration to the project.

Checklist

• Unit tests created/updated for any new code (where applicable).
• Run all tests with ./build.sh validate.
• Update the CHANGELOG.md.
• Update the README.md if necessary.

[confluent-cla-assistant]

🎉 All Contributor License Agreements have been signed. Ready to merge.
_{Please push an empty commit if you would like to re-run the checks to verify CLA status for all contributors.}

[alpinegizmo]

I played with this; it seems to work fine.

However, I found myself disoriented for two reasons:

• I found myself wishing that the README had been brought up automatically
• Once I read through the README I was surprised it told me about staging and solving the exercises, but nothing about how to actually get started with the exercises. I think we need to add a prominent link to CD in the README, to help out anyone who finds this repo without knowing how it connects to the course.

I think improving the README is unrelated to this PR.

[WadeWaldron]

@alpinegizmo I like the idea of opening the README by default. Took a quick look and figured out how to do that. Added that to the Gitpod configuration.

While I was in there, it made sense to add the link to the course, so I did that too.

[alpinegizmo]

Nice.