Adjust wording for clarity

Author: chrishtr

css-scroll-anchoring-1/Overview.bs

@@ -81,7 +81,7 @@ and close to the block start edge of its <a>optimal viewing region</a>.
 Note: If the user agent does not support the 'scroll-padding' property,
 the optimal viewing region of the scrolling box is equivalent to its <a>content area</a>.
 
-An anchor node can be any non-<a>atomic inline</a> <a>box</a>.
+An anchor node can be any <a>box</a> except one for a non-<a>atomic inline</a>.
 The anchor node is always a <a>descendant</a> of the <a>scrolling box</a>.
 In some cases, a scrolling box may not select any anchor node.