fix/typo flexible-voting-extension.md

[dedyshkaPexto]

Pull Request Title: Fix Typo in flexible-voting-extension.md

Description

This pull request fixes a minor typo in the flexible-voting-extension.md documentation file.

Changes Made:

• Corrected the spelling of "extention" to "extension" in the document title and body.

Context

This change enhances the readability and professionalism of the documentation. No functional code or additional content has been modified.

Checklist

• I have read the Contributing Guidelines.
• Changes adhere to the repository's style guide for documentation.
• No functional or behavioral changes were introduced.

Reviewer Notes

• Confirm that the typo has been corrected consistently.
• This change is limited to the correction of a single word, so minimal review effort is required.

Screenshots or Text (if applicable)

Before:

The Scopelift team built a Flexible Voting extention with support from Uniswap Grants Program.