Docs: Change example focus order

[louismaximepiton]

Description

Change the focus order of the examples.
Issue when the window is very small on long file names. See here the JS example on small viewports.

Motivation & Context

Better accessibility on focus order to have the content before the copy button.

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-40972--twbs-bootstrap.netlify.app/docsref

Related issues

NA

[julien-deramond]

I haven't reviewed the code yet, but this PR seems to bring a more logical order to the focusable elements:

1. File (optional)
2. Code
3. Edit on StackBlitz (optional)
4. Copy code

It feels more intuitive to inspect the code before attempting to copy it.

I'll wait for @patrickhlauke feedback before reviewing the actual code :)