Improve docs on Modals, Alerts, Offcanvas and Toasts close triggers examples

[hannahiss]

Description

• "Dismissal can be achieved with the data attribute on a button" changed to "Dismissal can be achieved with the data-bs-dismiss attribute on a button" for more understandable indication
• "using the data-bs-target" changed to "using the additional data-bs-target" for more complete indication
• change outside button class from btn-close to btn btn-primary since an outside button is unlikely to be a cross button

Motivation & Context

Makes the documentation more understandable and precise.

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-38182--twbs-bootstrap.netlify.app/
• For alerts for example: https://deploy-preview-38182--twbs-bootstrap.netlify.app/docs/5.3/components/alerts/#triggers

[mdo]

Thanks!