docs: fix modal JS examples, list numbering, and typos

[minirang]

Description

• Corrects the broken JavaScript modal example by properly fetching the modal instance via bootstrap.Modal.getInstance() and listening to the correct event (hidden.bs.modal).
• Fixes sequential list numbering in the Vite getting-started guide (from 3, 4 to 2, 3).
• Fixes minor typos and casing in the migration documentation (e.g., LibSass and .rounded-lg).

Motivation & Context

The previous JavaScript example for destroying a modal used an incorrect, non-existent event (shown.bs.hidden) and attempted to call .hide() and .dispose() in a way that would fail or cause unintended behavior. Updating this with getInstance and the proper event lifecycle ensures users can successfully copy-paste working code.

The list numbering and typos were also corrected to improve the overall clarity and professionalism of the documentation.

Type of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactoring (non-breaking change)
• Breaking change (fix or feature that would change existing functionality)

Checklist

• I have read the contributing guidelines
• My code follows the code style of the project (using npm run lint)
• My change introduces changes to the documentation
• I have updated the documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed

Live previews

• https://deploy-preview-{your_pr_number}--twbs-bootstrap.netlify.app/

Related issues

None. This was found while reviewing the documentation.

[julien-deramond]

Thanks for the various docs fixes @minirang, good catch :)

I've added c551406 so that we always use myModalEl var name each time we call document.querySelector('#myModal') for consistency in the page.

[minirang]

Thank you, @julien-deramond. I am glad to contribute to this project!