chore: include supported version of Webots in docs

[abanuelo]

Description

Making explicit mention that Scenic only supports Webots versions >= 2023a.

Issue Link

260

Checklist

• [ ] I have tested the changes locally via pytest and/or other means
• [ ] I have added or updated relevant documentation
• [ ] I have autoformatted the code with black and isort
• [ ] I have added test cases (if applicable)

Additional Notes

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 86.20%. Comparing base (308c351) to head (4764f0b).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #266 +/- ## ========================================== + Coverage 86.19% 86.20% +0.01% ========================================== Files 144 144 Lines 25041 25046 +5 ========================================== + Hits 21583 21590 +7 + Misses 3458 3456 -2 ```

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