[css-syntax] Remove now-irrelevant note about Selectors syntax.

Author: tabatkins

css-syntax/Overview.bs

@@ -471,11 +471,6 @@ Tokenization</h2>
 	Note: The type flag of hash tokens is used in the Selectors syntax [[SELECT]].
 	Only hash tokens with the "id" type are valid <a href="https://www.w3.org/TR/selectors/#id-selectors">ID selectors</a>.
 
-	Note: As a technical note,
-	the tokenizer defined here requires only three <a>code points</a> of look-ahead.
-	The tokens it produces are designed to allow Selectors to be parsed with one token of look-ahead,
-	and additional tokens may be added in the future to maintain this invariant.
-
 
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