[css-writing-modes] Add issues from www-style

Author: kojiishi

css-writing-modes/Overview.bs

@@ -892,9 +892,13 @@ Block Flow Direction: the 'writing-mode' property</h3>
     element is <em>not</em> propagated to the viewport. That special
     behavior only applies to the background and overflow properties.
 
+  <p class="issue">propagation of 'direction' from &lt;body&gt; <a href="https://readable-email.org/list/www-style/topic/re-css-writing-modes-css21-propagation-of-direction-from-body">www-style</a>
+
 <h4 id="svg-writing-mode">
 SVG1.1 'writing-mode' Values</h4>
 
+  <p class="issue">SVG should inherit writing-mode or not? <a href="https://lists.w3.org/Archives/Public/www-style/2015May/0150.html">www-style</a>
+
   <p>SVG1.1 [[!SVG11]] defines some additional values: ''lr'',
     ''lr-tb'', ''rl'', ''rl-tb'', ''tb'', and ''tb-rl''.