[css-writing-modes] Add id to the notes

Author: kojiishi

css-writing-modes/Overview.bs

@@ -2076,7 +2076,7 @@ Auto-sizing Block Containers in Orthogonal Flows</h4>
 
   <p class="issue"><a href="https://lists.w3.org/Archives/Public/www-style/2015Apr/0212.html">Defer proposal in ML</a> not resolved yet</p>
 
-  <div class="note">
+  <div class="note" id="orthogonal-shrink-to-fit">
   <p>
     This section defines that
     when a child box establishes an orthogonal flow,