_content/blog: fix ellipsis in vuln.md
_content/blog: fix ellipsis in vuln.md

Change-Id: I150bbc459a22f95229b5de0d27e584609d38077d
Reviewed-on: https://go-review.googlesource.com/c/website/+/428615
Reviewed-by: Tatiana Bradley <ed5904c3174de8861076818d9fdd7f7c949a16e6@golang.org>
Reviewed-by: Julie Qiu <e6cb64861edcc38971590ff27c111e0e672de045@google.com>

golang/website,golang/website,golang/website,golang/website,golang/website,golang/website,golang/website