Edit link option in home page

[lazarusA]

Is your feature request related to a problem? Please describe.

As of now, we can enable the Edit this page on GitHub on contents but not the index.md file, it would be nice have also an option for that.

Describe the solution you'd like

themeConfig: {
    editLink: {
      pattern: 'https://github.com/vuejs/vitepress/edit/main/docs/:path',
      text: 'Edit this page on GitHub'
      index: true
    }

Describe alternatives you've considered

No response

Additional context

No response

Validations

• Follow our Code of Conduct
• Read the docs.
• Read the Contributing Guidelines.
• Check that there isn't already an issue that asks for the same feature to avoid creating a duplicate.