@REP
I think a blog post would be appropriate. Granted many readers don't read the author's blog, so they probably wouldn't bother reading another form of notifying them of changes to a story.
There are two sides to that argument. While many readers don't follow blogs, posting blogs will often introduce your work to readers who may never have noticed it before (there are readers who specifically follow blog postings). But, even if those readers aren't interested your story, once you post a blog, anytime a reader has a question, they'll typically visit your blog to check on updates, so it's a way of making the information available.
Of course, much has been written about when to report changes, and the general rule of thumb is: if the changes substantially change the story (i.e. you add new chapters to an existing story, eliminate an entire subplot, or change the underlying plot, then you report it), but if you merely 'clean up' something, you don't (though, if it's a massive project, you generally announce why you're replacing the entire story with a newer, more updated version).