Rails Basic Validations: Update knowledge check link

[Monatric]

Because

The knowledge check link for failed validation is outdated. It does not work on version 8. The id #validations-overview-errors of the link seems to be for version 6.1. This fix should redirect to the correct and latest section of the guide and prevent confusion.

This PR

• Change the knowledge check link from the old version to the latest one.

Issue

Closes #XXXXX

Additional Information

Pull Request Requirements

• [x] I have thoroughly read and understand The Odin Project curriculum contributing guide
• [x] The title of this PR follows the location of change: brief description of change format, e.g. Intro to HTML and CSS lesson: Fix link text
• [x] The Because section summarizes the reason for this PR
• [x] The This PR section has a bullet point list describing the changes in this PR
• [x] If this PR addresses an open issue, it is linked in the Issue section
• [x] If any lesson files are included in this PR, they have been previewed with the Markdown preview tool to ensure it is formatted correctly
• [x] If any lesson files are included in this PR, they follow the Layout Style Guide