html: update URL in comment

Author: lusingander

src/html/escape.go

@@ -12,7 +12,7 @@ import (
 
 // These replacements permit compatibility with old numeric entities that
 // assumed Windows-1252 encoding.
-// http://www.whatwg.org/specs/web-apps/current-work/multipage/tokenization.html#consume-a-character-reference
+// https://html.spec.whatwg.org/multipage/parsing.html#numeric-character-reference-end-state
 var replacementTable = [...]rune{
 	'\u20AC', // First entry is what 0x80 should be replaced with.
 	'\u0081',