feat(docs): Make input autofocus in the /icons page

[danilo-leal]

What is the purpose of this pull request?

• [ ] New Icon
• [ ] Bug fix
• [ ] New Feature
• [x] Documentation update
• [ ] Other:

Description

This PR simply adds the autofocus attribute to the Input component on the /icons page. This allows users to immediately type their search query, which then avoids an extra click. Here's a quick video with the before & after:

https://github.com/user-attachments/assets/e33d9a9e-4791-4506-8646-7838f5095700

Love Lucide—we use it extensively at Zed! 😃 I basically have the docs tab open every day.

Before Submitting

• [x] I've read the Contribution Guidelines.
• [x] I've checked if there was an existing PR that solves the same issue.