Add Acronym practice exercise

[kephas]

It's missing for #48in24 week 7.

[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.

[kahgoh]

I noticed the commit is missing a number of changes:

• the track's config.json is missing the change to add the exercise
• the exercise is missing the .meta directory and its example.lfe, config.json and tests.toml
• the exercise is also missing .docs directory and its instructions.md file (and possible introduction.md if it exists)

These files can be obtained using configlet's sync command.

[kephas]

I pushed a new version according to the reviews.

[ErikSchierboom]

@kephas I can't re-open this PR. Could you recreate the PR and ping me once you've done that?