vc-comment-alist

vc-comment-alist is a variable defined in `vc.el'.
Its value is

((nroff-mode ".\\\"" ""))

Documentation:
Special comment delimiters for generating VC headers.
Add an entry in this list if you need to override the normal `comment-start'
and `comment-end' variables. This will only be necessary if the mode language
is sensitive to blank lines.

You can customize this variable.