[css-display-4] Link to background information in issues

Author: fantasai

css-display-4/Overview.bs

@@ -980,6 +980,15 @@ Display Order</h2>
 	of 'order', 'layout-order', and 'reading-order'
 	and discourage their misuse.
 
+	ISSUE(7387): See this
+	<a href="https://github.com/w3c/csswg-drafts/issues/7387#issuecomment-1217193918">
+	summary of how this all fits together and why</a>.
+
+	ISSUE: DOM needs a convenient reordering function
+	so that authors (even authors who don't usually write JS)
+	can easily perform source order reordering when necessary
+	instead of misusing 'order'.
+
 <h3 id='order-property'>
 Display Order Shorthand: the 'order' property</h3>