[css-grid] Add buglink to resolved value issue.

Author: tabatkins

css-grid/Overview.html

@@ -1209,6 +1209,7 @@ <h4 data-level=5.1.5 id=resolved-track-list><span class=secno>5.1.5 </span><span
 		In general, resolved values are the computed values,
 		except for a small list of legacy 2.1 properties.
 		Do we really want these properties to return the used value here?
+		<a href="https://www.w3.org/Bugs/Public/show_bug.cgi?id=16906">Bug about this.</a>
 
 
 <h3 data-level=5.2 id=grid-template-areas-property><span class=secno>5.2 </span><span class=content>

css-grid/Overview.src.html

@@ -1147,6 +1147,7 @@ <h4 id='resolved-track-list'>
 		In general, resolved values are the computed values,
 		except for a small list of legacy 2.1 properties.
 		Do we really want these properties to return the used value here?
+		<a href="https://www.w3.org/Bugs/Public/show_bug.cgi?id=16906">Bug about this.</a>
 
 
 <h3 id="grid-template-areas-property">