[css-anchor-position-1] Tweak wording in note

Author: fantasai

css-anchor-position-1/Overview.bs

@@ -1016,11 +1016,10 @@ or does not have a [=default anchor box=],
 this value behaves as ''<self-position>/center''
 and has no additional effect on how [=inset properties=] resolve.
 
-Note: Similar to 'position-area',
-when using ''anchor-center'',
+Note: When using ''anchor-center'', by default
 if the anchor is too close to the edge of the box's
 [=original containing block=],
-by default it will “shift” from being purely centered,
+it will “shift” from being purely centered,
 in order to remain within the [=original containing block=].
 See [[css-align-3#overflow-values]] for more details.