Added new JavaScript course for pl lang

[dr0er]

What does this PR do?

Add resources

For resources

Description

I've added a resource for learning JavaScript.

Why is this valuable (or not)?

It's a popular course for learning JavaScript in Poland.

How do we know it's really free?

A link I provided in .md file leads to a completely free playlist on YouTube website. The entire course content is visible to every user, not hidden behind any form of paywall.

For book lists, is it a book? For course lists, is it a course? etc.

Yes, it's online course.

Checklist:

• Read our contributing guidelines.
• 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.

Follow-up

• Check the status of GitHub Actions and resolve any reported warnings!

[github-actions]

Linter failed, fix the error(s):

free-programming-books/courses/free-courses-pl.md
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[github-actions]

Linter failed, fix the error(s):

free-programming-books/courses/free-courses-pl.md
1:1  warning  Missing newline character at end of file  final-newline  remark-lint

[Ajay-singh1]

Suggested change

	* [Zostań Programistą JavaScript](https://youtube.com/playlist?list=PLaRAejmsc8gGAs-Ml8aa4eLCkm6ESvdnN&si=aGm9u8lJl4B1_Fh3) - Kacper Szarkiewicz
	* [Kurs Javascript: Moduł 1: Poczatkujacy](https://youtube.com/playlist?list=PLaRAejmsc8gGAs-Ml8aa4eLCkm6ESvdnN&si=aGm9u8lJl4B1_Fh3) - Kacper Szarkiewicz

[Ajay-singh1]

Dont invent titles just put the title given in resource

[eshellman]

also, use www.youtube.com and remove the si parameter