[css-device-adapt] Add issue

Author: frivoal

css-device-adapt/Overview.bs

@@ -53,6 +53,13 @@ implementations are not fully interoperable and this specification is
 an attempt at standardizing the functionality provided by the
 viewport <code class=html>&lt;META&gt;</code> tag in CSS.
 
+Issue: This specification is written from an implementation centric point of view,
+making it arguably difficult to read.
+Significant editorial work may be needed
+to make it more understandable to different audiences.
+It also should clarify which viewport is referred to by various js APIs.
+See <a href="http://www.quirksmode.org/blog/archives/2015/09/a_new_device_ad.html">this blog post by ppk</a>
+for a good discussion of these issues.
 
 <h2 id="values">
 Values</h2>