publications - I discovered a mistake in my own published workshop paper, how do I handle errata?

I am PhD student and the main author of a research-in-progress report in computer science. The paper is already published at a workshop (in the proceedings, this is not a journal paper) and was presented there a few months ago.

While continuing to work on the topic of the paper, I discovered a mistake I did in the already published workshop paper. A value that is referred to twice in the paper is wrong; it is still unusually high but lower than reported. The value is also mentioned in the summary of the paper. First I told my coauthors who sit in the next room in the same institute.

Now I want to publish an Erratum on my academic website.

My first idea is to publish a text file next to the download like that is labeled "erratum" (it is a single mistake). As an example for this "text file", I looked at the following webpage.

My second idea is to change the author version of my workshop paper that is downloadable as PDF file from my website. My current idea is to solve this via a footnote in the PDF version of the paper. So how would I handle that? Do I correct the value and add a footnote saying that the original published value was wrong and explain the mistake? The other option that I think is unsuitable is the following: to leave the wrong value in the paper and add a footnote that explains that this value was a mistake and give the correct value in the footnote?

Also, are there websites on how to handle errata for conference/workshop papers in technical fields like computer science? Please note also that in my field conference papers are quite important (e.g., the POPL conference) while in some other fields only journal papers count (sort of).