docs(tour): clarify usefulness of context bounds with type classes

[Dev-CodeBox]

This PR updates the Implicit Parameters tour page to:

• Highlight that context bounds are especially useful with type classes, where a type requires an associated contextual value.
• Ensure the explanation of context bounds and examples are clear and concise for both Scala 2 and Scala 3.
• Minor formatting and wording improvements for readability

[bishabosha]

this doesnt include the error in the output, but in this case the error message is the point