Forms and Data Handling: Change incorrect link in Knowledge Check

[Anshuman-Jha-01]

Because

This PR updates an incorrect link under Knowledge Check section of Forms and Data Handling topic.

This PR

• Fixes the incorrect link which leads to a page about SQL Injection in the final question in the Knowledge Check section to a link that leads to a section about escaping HTML characters.

Issue

Closes #29515

Pull Request Requirements

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