Although minor changes are, well, minor, it is still a good idea to keep others informed on what they are. I have learned the hard way that a simple trivial change can sometimes make a big difference to another who may be using the script in a way you didn't think about. It's also just a good practice to keep.
I sometime just use the generic "coding improvements" when the edits do not effect the user at all, merely imrpove performance, such as shortening a method down after you saw some redundant lines of code, etc.