Fix: removeSignature docstring style in Transaction.h

[ak004]

Description:
Update the removeSignature docstring in Transaction.h to match the documentation style used throughout the file.

• Use imperative voice to align with other method comments
• Clarify wording to distinguish it from removeAllSignatures
• Fix @throws formatting and phrasing

Related issue(s):

Fixes #1226

Notes for reviewer:
This change updates documentation only. No functional code or public API behavior was modified.

Checklist

• Documented (Code comments, README, etc.)
• Tested (unit, integration, etc.)

[github-actions]

Hey @ak004 👋 thanks for the PR!
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PR Checks

✅ DCO Sign-off -- All commits have valid sign-offs. Nice work!

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✅ Issue Link -- Linked to #1226 (assigned to you).

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[ak004]

The commit has now been GPG signed and force-pushed to the branch.
Please let me know if any further changes are needed. Thank you!

[rwalworth]

Thanks for the contribution @ak004! The docstring text itself looks great and matches the issue requirements exactly. I found one formatting issue below that needs to be fixed before we can merge - once that's addressed, we'll be good to go. Let me know if you have any questions!

[rwalworth]

LGTM - the indentation is fixed and everything matches the requirements. Running the workflows now and will get this merged!