fix: add creator name to a perl course in free-courses-en.md

[RUIZEN9]

What does this PR do?

Improve repo

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Description

Added creator name to perl course in free-courses-en.md

Why is this valuable (or not)?

It keeps the repository standardized

Checklist:

• Search for duplicates.
• Include author(s) and platform where appropriate.
• Put lists in alphabetical order, correct spacing.
• Add needed indications (PDF, access notes, under construction).
• Used an informative name for this pull request.

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