docs: clarify nested loop usage in layout tutorial

[harshyadavDeveloper]

Description of what this PR is changing or adding, and why:

Clarifies the challenge instructions in the layout tutorial by
correcting the description of the guess variable type.

The previous wording incorrectly implied that guess itself was a
record with the type ({String char, HitType type}), when it is
actually a collection of records. The updated text explains that each
element in guess is a record and explicitly mentions using a nested
loop to iterate over the letters.

This aligns the tutorial instructions with the provided solution code
and avoids confusion for readers attempting the challenge.

Issues fixed by this PR (if any):

Fixes #13422

PRs or commits this PR depends on (if any):

None.

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[harshyadavDeveloper]

@sfshaza2 This PR updates the tutorial wording to clarify the nested loop and correct the guess variable type description. Would appreciate a review when you have time. Thanks!

[gemini-code-assist]

Code Review

This pull request updates the tutorial documentation in layout.md by clarifying that each element in the guess variable is a record and adding a hint to use a nested loop for iterating over letters. I have no feedback to provide as there were no review comments.

[piedcipher]

LGTM