Reference #sctn-extensions in extensions parameter descriptions

index.bs

@@ -2618,6 +2618,8 @@ optionally evidence of [=user consent=] to a specific transaction.
     ::  The [=[RP]=] MAY use this OPTIONAL member to provide [=client extension inputs=]
         requesting additional processing by the [=client=] and [=authenticator=].
         For example, the [=[RP]=] may request that the client returns additional information about the [=credential=] that was created.
+
+        The extensions framework is defined in [[#sctn-extensions]].
         Some extensions are defined in [[#sctn-defined-extensions]];
         consult the IANA "WebAuthn Extension Identifiers" registry [[!IANA-WebAuthn-Registries]] established by [[!RFC8809]] for an up-to-date list
         of registered [=WebAuthn Extensions=].
@@ -2980,6 +2982,8 @@ an assertion. Its {{PublicKeyCredentialRequestOptions/challenge}} member MUST be
     :   <dfn>extensions</dfn>
     ::  The [=[RP]=] MAY use this OPTIONAL member to provide [=client extension inputs=]
         requesting additional processing by the [=client=] and [=authenticator=].
+
+        The extensions framework is defined in [[#sctn-extensions]].
         Some extensions are defined in [[#sctn-defined-extensions]];
         consult the IANA "WebAuthn Extension Identifiers" registry [[!IANA-WebAuthn-Registries]] established by [[!RFC8809]] for an up-to-date list
         of registered [=WebAuthn Extensions=].