[css-syntax] Add missing "anything else" case in Check if three code points would start an identifier.

Author: SimonSapin

css-syntax/Overview.bs

@@ -1531,6 +1531,10 @@ Check if three code points would start an identifier</dfn></h4>
 			If the first and second <a>code points</a> <a>are a valid escape</a>,
 			return true.
 			Otherwise, return false.
+
+		<dt>anything else
+		<dd>
+			Return false.
 	</dl>
 
 <h4 id="starts-with-a-number">
@@ -3438,6 +3442,7 @@ Acknowledgments</h2>
 		Johannes Koch,
 		呂康豪 (Kang-Hao Lu),
 		Marc O'Morain,
+		Raffaello Giulietti,
 		Simon Pieter,
 		and Zack Weinberg.