The edit suggestion changes c:\\foo.txt to c:\\test1\\foo.txt to demonstrate that directories need to have their backslashes escaped as well. The reviewers likely thought that it was already clear that all backslashes, regardless of what they're delimiting, have to be doubled up to be escaped. In that light, the edit looked like it was just using a different example path, which doesn't add anything. Admittedly, if you haven't used programs or languages that require this kind of escaping, it might not jump out at you. (But now you know!)
General advice follows.
Strictly speaking, edit suggestions shouldn't attempt to change the technical details, since reviewers aren't expected to judge technical accuracy. It's debatable whether providing a potentially-more-useful example is a technical change, but some would say that altering code intended to be typed/run changes the meaning of the answer. To play it safe, leave a comment to share your newly discovered clarification.
Post owners receive notifications about edit suggestions, and if they get to it before others review the suggestion, their vote is binding.
