Warn when changing the keybind for 'Undo changes' to Ctrl-Z

I was fiddling around with the settings when I saw the default hotkey for undo is `Ctrl-U`, and I thought to myself "Oh, and why would any hotkey that undo stuff not be `Ctrl-Z`?" and properly decided to *correct* this oversight. Later when I was writing lines and lines of instruction in the assembler, I absentmindedly hit `Ctrl-Z` *AND ALL THE CHANGES I DID WERE GONE IN AN INSTANT -*

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Please show a warning when the keybind is changed to `Ctrl-Z`. Or maybe clarify just what **exactly** does *"most recent changes"* in the phrase "undo the most recent changes in the current editor" mean. Or maybe add a redo button.