[css-sizing-3] Remove duplicated Note in Note. w3c#6072 (comment)

Author: fantasai

css-sizing-3/Overview.bs

@@ -894,7 +894,7 @@ and if its containing block was <em>infinitely</em>-sized in that axis.
 The [=min-content size=] and [=max-content size=] are collectively referred to
 as the [=intrinsic sizes=].
 
-Note: Note that when the box has a [=preferred aspect ratio=],
+Note: When the box has a [=preferred aspect ratio=],
 size constraints in the opposite dimension will transfer through
 and can affect the ''width/auto'' size in the considered one.
 See <a href="https://www.w3.org/TR/CSS2/visudet.html">CSS2&sect;10</a>.