[css-display-3] HTML should be an informative, rather than normative, bibliographic reference

&lsquo;[HTML]&rsquo; is in the Normative References[1], but it seems the only mention of things defined by HTML is just after the words "For example" in section 2.5[2]. I think &lsquo;[HTML]&rsquo; should be in the Informative References instead.

[1] https://www.w3.org/TR/2017/WD-css-display-3-20170126/#normative
[2] https://www.w3.org/TR/2017/WD-css-display-3-20170126/#box-generation
