Merge pull request #1131 from w3c/issue-1128-authenticator-examples

Add examples of authenticator types to Authenticator definition

index.bs

@@ -554,6 +554,11 @@ The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "S
     cryptographically signing and returning, in the form of an [=Authentication Assertion=], 
     a challenge and other data presented by a [=[WRP]=] (in concert with the [=[WAC]=]).
 
+    A [=[WAA]=] could be, for example, a dedicated USB or wireless device separate from the [=client device=],
+    a dedicated hardware subsystem integrated into the [=client device=],
+    or a software component of the [=client=].
+    [=Authenticators=] can report their type and security characteristics via [=attestation=].
+
 : <dfn>Authorization Gesture</dfn>
 :: An [=authorization gesture=] is a physical interaction performed by a user with an authenticator as part of a [=ceremony=],
     such as [=registration=] or [=authentication=]. By making such an [=authorization gesture=], a user [=user consent|provides