docs: improve skeleton story examples

[niketchandivade]

Summary

• Update the BlockWrapper story to use four skeletons, matching the four comparison boxes.
• Clarify the description in RegressionTest133 for better readability.

Changes

These changes improve consistency across the Storybook examples and make the regression test description clearer.

Testing

• Reviewed the updated Storybook examples.
• Ran lint and type checks.

[srmagura]

Can you explain why this change is helpful?

[niketchandivade]

@srmagura The count change makes the number of skeleton blocks match the four Box examples, keeping the demo consistent. The wording change clarifies the description of the pseudo-element positioning issue. That said, I understand these are minor improvements and am happy to drop the wording change if it doesn't add enough value.