fix: Update wizard's i18nStrings.submitButton description

[cansuaa]

Description

Updated wizard's i18nStrings.submitButton description to clarify that this value is not supported in Cloudscape's i18nProvider.

Related links, issue #, if available: AWSUI-60108

How has this been tested?

Review checklist

The following items are to be evaluated by the author(s) and the reviewer(s).

Correctness

• Changes include appropriate documentation updates.
• Changes are backward-compatible if not indicated, see CONTRIBUTING.md.
• Changes do not include unsupported browser features, see CONTRIBUTING.md.
• Changes were manually tested for accessibility, see accessibility guidelines.

Security

• If the code handles URLs: all URLs are validated through the checkSafeUrl function.

Testing

• Changes are covered with new/existing unit tests?
• Changes are covered with new/existing integration tests?

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.34%. Comparing base (d1ff27e) to head (2d285c9).
Report is 42 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3094   +/-   ##
=======================================
  Coverage   96.34%   96.34%           
=======================================
  Files         779      779           
  Lines       21913    21913           
  Branches     7502     7502           
=======================================
  Hits        21112    21112           
  Misses        749      749           
  Partials       52       52           

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