Remove misleading gz extension

[joeytwiddle]

The --delete option does not work on compressed archives, so the example should not show a compressed archive!

Edit: My brain was also lacking juice when I wrote this. I wanted to address the comment, but couldn't decide how. In retrospect, I could have prefixed: "The comment says correctly that --delete does not ..."

[terminalforlife]

This is explained in the comment immediately above the line. Actually, no, I agree, this is a good idea. Makes it clearer! 😆 My brain hasn't yet switched on. 😫