badblocks - text could be improved for write tests

[JohnVeness]

Hello. For people who only run badblocks occasionally, and want to do a write test, it is currently not clear that the stages like "Testing with pattern 0xaa", with progress from 0% to 100%, is only the write stage, and there will be a separate read/compare stage after that.

Maybe the text for the "testing" stage be changed to "Writing pattern 0xaa" etc., to make it more clear that when that gets to 100%, it still won't be done?