Because

Rails 8 introduced a slightly different (and better/more secure) syntax for strong parameters (see: rails changelog)

This method is mentioned in their updated Rails guides (which are part of learner's assigned reading) as the preferred way to handle strong parameters. This is causing confusion as there's a discrepancy with what learners read about strong parameters in the lesson vs. in the rails guides. We could point learners to an older version of the guides on that reading, but I think this is a simple enough fix and doesn't introduce any (easily forgettable) maintenance overhead of eventually needing to go back and set the guides back to default/modern state.

This PR

• Updates controllers lesson to use the new #expect syntax.
• Mentions the permit().require() chain as an older alternative that learners may run into.
• Updates other examples of strong parameters throughout the Rails course to use the newer syntax.
• Fixes lint issues in the controllers lesson.
• Introduces small clarification on what exactly params is inside of a controller.

Issue

Closes #29121

Additional Information

Pull Request Requirements

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