Add test for POV based on instructions

Hello, I’ve seen some solutions that passes the current tests but don’t pass the proposed example from the instructions, so I added to the test suite.

This is the PR that I created with the new test: Add test for POV based on instructions by Bechma · Pull Request #2111 · exercism/rust · GitHub

You should give this a read: Suggesting Exercise Improvements | Exercism's Docs

It contains some very useful context for what goes into those tests.