Restore note that only one credential property is defined

index.bs

@@ -7344,6 +7344,10 @@ During a transition from the FIDO U2F JavaScript API, a [=[RP]=] may have a popu
 
 This [=client extension|client=] [=registration extension=] facilitates reporting certain [=credential properties=] known by the [=client=] to the requesting [=[WRP]=] upon creation of a [=public key credential source=] as a result of a [=registration ceremony=].
 
+At this time, one [=credential property=] is defined: the [=resident key credential property=]
+(i.e., [=client-side discoverable credential property=]).
+
+
 : Extension identifier
 :: `credProps`