fix proper subset tweak (#542)

index.bs

@@ -2022,8 +2022,8 @@ When registering a new credential, represented by a {{AuthenticatorAttestationRe
 4. Verify that the {{CollectedClientData/tokenBindingId}} in |C| matches the [=Token Binding ID=] for the TLS connection over
     which the attestation was obtained.
 
-5. Verify that the {{CollectedClientData/clientExtensions}} in |C| is a proper subset of the extensions requested by the RP
-    and that the {{CollectedClientData/authenticatorExtensions}} in |C| is also a proper subset of the extensions requested by
+5. Verify that the {{CollectedClientData/clientExtensions}} in |C| is a subset of the extensions requested by the RP
+    and that the {{CollectedClientData/authenticatorExtensions}} in |C| is also a subset of the extensions requested by
     the RP.
 
 6. Compute the hash of {{AuthenticatorResponse/clientDataJSON}} using the algorithm identified by
@@ -2104,8 +2104,8 @@ When verifying a given {{PublicKeyCredential}} structure (|credential|) as part
 6. Verify that the {{CollectedClientData/tokenBindingId}} member of |C| (if present) matches the [=Token Binding ID=] for the
     TLS connection over which the signature was obtained.
 
-7. Verify that the {{CollectedClientData/clientExtensions}} member of |C| is a proper subset of the extensions requested by the
-    [=[RP]=] and that the {{CollectedClientData/authenticatorExtensions}} in |C| is also a proper subset of the extensions
+7. Verify that the {{CollectedClientData/clientExtensions}} member of |C| is a subset of the extensions requested by the
+    [=[RP]=] and that the {{CollectedClientData/authenticatorExtensions}} in |C| is also a subset of the extensions
     requested by the [=[RP]=].
 
 8. Verify that the [=RP ID=] hash in |aData| is the SHA-256 hash of the [=RP ID=] expected by the [=[RP]=].