[css-writing-modes] Suggest use <bdi> tag also

[ebraminio]

There are similar recommendations in https://drafts.csswg.org/css-writing-modes-3/ "[..] we recommend HTML authors to use the HTML dir attribute and element [..]" and the one other in "[..] we recommend HTML authors to use the HTML dir attribute, <bdo> element, and appropriate [..]" and there is a copy in https://drafts.csswg.org/css-writing-modes-4/ I believe <bdi> is also worth to mention here, maybe more than <bdo>.