[selectors-4] Fix changes list for :blank.

Author: fantasai

selectors-4/Overview.bs

@@ -3870,8 +3870,10 @@ Changes</h2>
 		(<a href="https://github.com/w3c/csswg-drafts/issues/2143">Issue 2143</a>)
 		<li>Renamed '':matches()'' to '':is()''.
 		(<a href="https://github.com/w3c/csswg-drafts/issues/3258">Issue 3258</a>)
-		<li>Removed '':blank'' and defined '':empty'' to ignored white-space&ndash;only nodes.
+		<li>Redefined '':empty'' to ignore white-space&ndash;only nodes.
 		(<a href="https://github.com/w3c/csswg-drafts/issues/1967">Issue 1967</a>)
+		<li>Redefined '':blank'' to represent empty user input, rather than empty elements.
+		(<a href="https://github.com/w3c/csswg-drafts/issues/1283">Issue 1283</a>)
 		<li>Changed the specificity of '':is()'', '':where()'', and '':nth-child()''
 		to not depend on which selector argument matched.
 		(<a href="https://github.com/w3c/csswg-drafts/issues/1027">Issue 1027</a>)