[css-grid-1][css-grid-2] Clarify that <'grid-template'> serialization is preferred if 'grid' is ambiguous. w3c#7805

Author: tabatkins

css-grid-1/Overview.bs

@@ -2665,6 +2665,11 @@ Grid Definition Shorthand: the 'grid' property</h3>
 		</pre>
 	</div>
 
+	When serializing,
+	if all the 'grid-auto-*' longhands have their initial values,
+	the 'grid-template' syntax is used.
+
+
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css-grid-2/Overview.bs

@@ -2820,6 +2820,11 @@ Grid Definition Shorthand: the 'grid' property</h3>
 		</pre>
 	</div>
 
+	When serializing,
+	if all the 'grid-auto-*' longhands have their initial values,
+	the 'grid-template' syntax is used.
+
+
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