Comment 1 for bug 2011287

An initial look at https://validator.w3.org/check?uri=https%3A%2F%2Fxubuntu.github.io%2Fxubuntu-docs%2Fuser%2FC%2Findex.html&charset=%28detect+automatically%29&doctype=Inline&group=0&ss=1&outline=1&No200=1&verbose=1 may pin this on DocBook. We're possibly at the wrong point in cadence to be looking at upgrading the XSLT stylesheets we have for DocBook but that may alleviate this.