duplicate paragraph under "Exclude sensitive information from version control"

[RichardP-tt]

Unless it's a cunning reinforcement technique, the paragraph starting "It is again worth stressing the importance of not committing sensitive" is a duplicate of the previous one and could be removed: https://github.com/best-practice-and-impact/qa-of-code-guidance/blob/611df2c0e71d869d11042194c7e13addbbf5f0a6/book/version_control.md?plain=1#L86C1-L86C1