Add Scala http4s example to docs (server-examples)

[martinprobson]

Description

Documentation update only - Added Scala (http4s) example to server examples page.

Testing

website checked locally with Zola

Checklist

• [X] I have read the contribution guidelines
• [X] I have targeted this PR against the correct branch (master for website changes, dev for source changes)
• [X] This is either a bugfix, a documentation update, or a new feature that has been explicitly approved via an issue
• [ ] I ran the test suite locally (npm run test) and verified that it succeeded