cmd/relnote: include closing dd tags in HTML output
cmd/relnote: include closing dd tags in HTML output

In HTML5, closing dd tags are optional, meaning it is okay to either
include them or exclude them. For the purpose of writing the release
notes HTML file, which involves many people collaborating, it's less
costly to always include optional HTML tags.

This can eliminate the need for doing so manually, like in CL 217701,
CL 245979, and so on.

Change-Id: Idc16ea61e2b9624d1aa48543df2b913936993909
Reviewed-on: https://go-review.googlesource.com/c/build/+/260497
Trust: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>
Run-TryBot: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>
TryBot-Result: Go Bot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Alexander Rakoczy <60c6d277a8bd81de7fdde19201bf9c58a3df08f4@golang.org>

golang/build,golang/build,golang/build,golang/build