[css-inline] add link to inline issue

Author: dauwhe

css-inline-3/Overview.bs

@@ -989,7 +989,9 @@ Initial Letter Wrapping: the 'initial-letter-wrap' property</h3>
 			</div>
 
 			Issue: Do we need an unconditional ''first''?
-			(I.e. Should we rename this value to ''auto'' and add a ''first'' value that does not check for spaces?)
+			(I.e. Should we rename this value to ''auto'' and add a ''first'' value 
+			that does not check for spaces?) See GitHub issue 
+			<a href="https://github.com/w3c/csswg-drafts/issues/410">410</a>
 
 		<dt><dfn>all</dfn></dt>
 		<dd>