[css-grid-3][editorial] Simplify wording by re-using existing terminology.

Author: fantasai

css-grid-3/Overview.bs

@@ -1080,8 +1080,7 @@ Sizing Grid Containers</h2>
 	[[css-grid-2#intrinsic-sizes|Sizing Grid Containers]] works the same as for regular [=grid containers=]
 	but with the following addendum for the [=stacking axis=]:
 	The <a>max-content size</a> (<a>min-content size</a>) of a [=grid container=] in the [=stacking axis=]
-	is the largest distance between the [=grid container's=] [=content-box=] [=start=] edge
-	and the maximum [=margin-box=] end of all the items,
+	is the size of the [=masonry box=] in that axis
 	when sized under a <a>max-content constraint</a> (<a>min-content constraint</a>).
 
 	<div class="example">