Use Title: meta instead of explicit <h1>

Author: tantek

css-transforms-1/Overview.bs

@@ -1,5 +1,5 @@
-<h1>CSS Transforms Module Level 1</h1>
 <pre class='metadata'>
+Title: CSS Transforms Module Level 1
 Status: ED
 Work Status: Refining
 ED: https://drafts.csswg.org/css-transforms/