Added an explanation for the Posts Block query arguments filter

[VictorMonk]

…dified

🎫 #[Jira Ticket]

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Checklist

• I have performed a self-review.
• No unrelated files are modified.
• No debugging statements exist (Ex: console.log, error_log).
• There are no warnings or notices in the wordpress error log.
• Passes all tests (linting, acceptance, & unit)

Block specific checklist (where relevant)

• Tested with an existing instance of this block .
• Tested creating a new instance of this block.
• Tested with Dynamic content & Elements.