Clarify when "string" should be used (and be escaped), and when "template.HTML" should be used (no need to escape) And help PRs like #29059 , to render the error messages correctly.
Before:  After:   --------- Co-authored-by: silverwind <me@silverwind.io> Co-authored-by: Giteabot <teabot@gitea.io> Co-authored-by: wxiaoguang <wxiaoguang@gmail.com> Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>