v3.15.0

✨ New Features

• 055d64d - Add xml2rfc class to HTML body element (PR #847 by @martinthomson)
• 7fec225 - Add classes to xref (PR #867 by @martinthomson)

🐛 Bug Fixes

• cc6b083 - Fix table colspan issue in text format (PR #886 by @kesara)
• 2475447 - Include the published date when ipr is none (PR #897 by @kesara)