Is it by e.g. adding "update sections", where new information is added at the bottom, so the progress is easy to follow, or is it better to just merge the progress into the question itself, keeping it concise and easier for newcomers to read, and returning people will see the markup of the changes anyway?
Please do yourself and others a favor and don't add the following to your question:
EDIT1: Yeah I've checked that Foo is deleted.
Edit197 in response to @someone: Yes, the folder exists.
That's not how a coherent question looks like. If you find out something new, work it into the text. Make your question pleasant to read, and structure it appropriately. Start by describing your situation, then your attempts to solve the problem.
So, rather do it like this, where square brackets denote text you just added:
I can't open Something. [Although I've checked that Foo is deleted, it still assumes the file is there. I've made sure the folder exists.] When I restart my computer, everything's fine again.
When you've done so, use the Edit Summary to state what you updated. This will make it easier to follow your question's revisions.
The idea is: Make it easy for new visitors to read your question and immediately grasp what the issue is. Don't make them scroll to the bottom to look for teeny-tiny bits of important information if that could as well have been in the actual text.
Those who are following you in comments will see your edits and know how you responded to them. There's no need to explicitly state an update in your question. That's why we have revisions, and everybody's free to click the edited… link and check for themselves.
I know it's common practice – especially in forums – to explicitly disclose edits to a post. But Stack Exchange is not a forum. Your questions are the single most important piece of information. There's no thread to read, and there's no chronological component to the eye of the visitor who seeks a solution to a similar problem. That's why there's really no need to clutter a question like this – you'll leave everybody confused. And remember that 90% of our traffic is from search engines — not regular users.