Sign-in page example update

[thomascavanagh-okta]

Description:

• What's changed? Add the changes in this PR: Update index.md #6044
• Is this PR related to a Monolith release? No

Resolves:

• OKTA-XXXXXX

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[okta-prod-github-app]

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Article	Total score Required:80	Word and phrases (Brand, terms) Preferred: 80	Correctness (Spelling, grammar) Preferred: 80	Clarity (Readability) Preferred: 80	Inclusive language (+ accesibility) Preferred: 80
✅ packages/@okta/vuepress-site/docs/guides/custom-widget/main/index.md	93	89	87	97

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