Add a note to ensure consistency with 'Defining string' section of [international-spec] (#517)

Co-authored-by: Martin Thomson <[email protected]>
Co-authored-by: Jeffrey Yasskin <[email protected]>

Author: 3 people

index.bs

@@ -2462,7 +2462,12 @@ or by adding separate, otherwise identical APIs which take {{BigInt}} and {{Numb
 This risks losing precision through implicit conversions,
 which defeats the purpose of {{BigInt}}.
 <h3 id="idl-string-types">Represent strings appropriately</h3>
-
+<div class="note">
+This section is meant to be mutually consistent with
+the [[international-specs#char_string|Defining string]] section
+of [[international-specs]].
+Please report any discrepancies that may happen as the documents evolve.
+</div>
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