[css-anchor-position][editorial] Fix wording. Closes #11029

Author: tabatkins

css-anchor-position-1/Overview.bs

@@ -412,7 +412,7 @@ in anchor positioning.
 		per the effects of 'anchor-scope' on |positioned el|
 		or its ancestors.
 
-	* |possible anchor| is painted strictly before |positioned el|,
+	* |possible anchor| is laid out strictly before |positioned el|,
 		aka one of the following is true:
 		* |positioned el| is [=in a higher top layer=] than |possible anchor|
 		* Both elements are [=in the same top layer=]