Added a loophole for secure contexts not using https

Clients today want to allow localhost on http, but are forbidden by spec due to scheme validation

index.bs

@@ -1341,7 +1341,7 @@ The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "S
         Note: An [=RP ID=] is based on a [=host=]'s [=domain=] name. It does not itself include a [=scheme=] or [=port=], as an [=origin=] does. The [=RP ID=] of a [=public key credential=] determines its <dfn>scope</dfn>. I.e., it <dfn>determines the set of origins on which the public key credential may be exercised</dfn>, as follows:
 
             - The [=RP ID=] must be equal to the [=determines the set of origins on which the public key credential may be exercised|origin=]'s [=effective domain=], or a [=is a registrable domain suffix of or is equal to|registrable domain suffix=] of the [=determines the set of origins on which the public key credential may be exercised|origin=]'s [=effective domain=].
-            - The [=determines the set of origins on which the public key credential may be exercised|origin=]'s [=scheme=] must be `https`.
+            - The [=determines the set of origins on which the public key credential may be exercised|origin=]'s [=scheme=] must be `https`, or considered [=a secure context|secure contexts=] .
             - The [=determines the set of origins on which the public key credential may be exercised|origin=]'s [=port=] is unrestricted.
 
         For example, given a [=[RP]=] whose origin is `https://login.example.com:1337`, then the following [=RP ID=]s are valid: `login.example.com` (default) and `example.com`, but not `m.login.example.com` and not `com`.