[css-logical] Clarify that border-inline/block set both affected sides to the same value only. #3519

Author: fantasai

css-logical-1/Overview.bs

@@ -657,9 +657,13 @@ the 'border-block-start', 'border-block-end', 'border-inline-start', 'border-inl
 
   These two <a>shorthand properties</a> set the
   'border-block-start' &amp; 'border-block-end'
-  and
+  or
   'border-inline-start' &amp; 'border-inline-end',
-  respectively.
+  respectively,
+  both to the same style.
+
+  <!-- intentionally cannot set two sides independently;
+       see discussion in https://github.com/w3c/csswg-drafts/issues/3519 -->
 
 <h3 id="border-radius-properties">
 Flow-relative Corner Rounding: