feat(voice-tone): Add active & passive voice example

Add an example of active and passive voice to the Voice & Tone page.

When writing copy, I need to get reminded about what is an active and passive voice because I tend to lean towards passive voice.

I like the example used in the Grammarly post about active and passive voice of "Monkeys adore bananas." vs "Bananas are adored by monkeys." respectively.

I created this MR to have a quick example that relates closer to the GitLab product