📝 Mention mqt-cc in handbook

[denialhaag]

Description

This PR updates the handbook to mention mqt-cc more prominently.

Checklist

• The pull request only contains commits that are focused and relevant to this change.
• I have added appropriate tests that cover the new/changed functionality.
• I have updated the documentation to reflect these changes.
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• I have reviewed my own code changes.

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[denialhaag]

@burgholzer, is this roughly what you had in mind? Is there anything else we want to do before a release? 🤔

[burgholzer]

Just one thought 💭

[burgholzer]

Do we really want to change that? This could silently break the docs here, right?
Potentially, we should even link to the versions that we pin in our requirements so that links are guaranteed to be stable. Just a thought.

[denialhaag]

This allows us to control the default version via Read the Docs. For most repositories, this is pointing to stable now, but some still use latest because we still need to release a new stable version (in particular, MQT QECC). That said, I see the point of pinning explicit versions here. I can do that later!