In questions/answers we type keyboard keys using
<kbd>KEY</kbd> which renders KEY. It does not work in comments. How can one type keyboard keys in comments?
Comments provide only a limited amount of markdown formatting, including italic, bold,
code (via single/double backticks), magic/shorthand links (for sites
[tex.se] or tag
[tag:tag] or...), regular links (like
[text](URL)). This excludes the use of HTML tags (like
<strong>bold</strong>) and the shorthand image inclusion format
![text](imageURL) commonly used in posts.
So there's not HTML
</kbd> keyboard tag formatting supported.
Reference: Markdown help - comment formatting