SSH pull repository mirroring was introduced in 9.5, not 9.15

What does this MR do?

Fix a typo in docs

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Documentation created/updated
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #3267 (closed)