Poniedzialek -> Poniedziałek (changed "l" to "ł" letter)

Pull request checklist

Please check if your PR fulfills the following requirements:

• Tested the changes
• Build (/path/to/php cli.php cmd=build) was run locally and any changes were pushed

Pull request type

Please check the type of change your PR introduces:

• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Other (please describe):

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this introduce a breaking change?

• Yes
• No

Docs need to be updated?

• Yes
• No

Other information