Update key features and tags

[grzegorz-bielski]

In here I noticed that the Lazy computation point in key features is not really correct and could be misleading.

I also updated other key features and tags to better showcase contemporary Scala's strengths.

[github-actions]

Hello. Thanks for opening a PR on Exercism 🙂

We ask that all changes to Exercism are discussed on our Community Forum before being opened on GitHub. To enforce this, we automatically close all PRs that are submitted. That doesn't mean your PR is rejected but that we want the initial discussion about it to happen on our forum where a wide range of key contributors across the Exercism ecosystem can weigh in.

You can use this link to copy this into a new topic on the forum. If we decide the PR is appropriate, we'll reopen it and continue with it, so please don't delete your local branch.

If you're interested in learning more about this auto-responder, please read this blog post.

---

Note: If this PR has been pre-approved, please link back to this PR on the forum thread and a maintainer or staff member will reopen it.

[grzegorz-bielski]

Hello, @ErikSchierboom.

This is a small follow-up to the recent PR. Please take a look 🙇

[ErikSchierboom]

It this ready to be merged?

[grzegorz-bielski]

@ErikSchierboom yes!