Change "WebAuthn Relying Party" to just "Relying Party"

Added text saying don't mistake this for other standards' Relying Party. I think WebAuthn is now sufficiently different than OAuth to make this change.

index.bs

@@ -14,8 +14,8 @@ Editor: Jeff Hodges, PayPal, Jeff.Hodges@paypal.com
 Editor: Michael B. Jones, Microsoft, mbj@microsoft.com
 Editor: Rolf Lindemann, Nok Nok Labs, rolf@noknok.com
 group: webauthn
-Text Macro: RP WebAuthn Relying Party
-Text Macro: RPS WebAuthn Relying Parties
+Text Macro: RP Relying Party
+Text Macro: RPS Relying Parties
 Text Macro: INFORMATIVE <em>This section is not normative.</em>
 Text Macro: WAC WebAuthn Client
 Ignored Vars: op, alg, type, algorithm
@@ -206,10 +206,16 @@ NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and
 	<a>authenticator</a>) work in concert to create a <a>scoped credential</a> and associate it with the user's <a>[RP]</a>
 	account. Note that this includes employing <a>user verification</a>.
 
+: <dfn>[RP]</dfn>
+:: The entity whose web application utilizes the <a>Web Authentication API</a> to register and authenticate users. See
+    <a>Registration</a> and <a>Authentication</a>, respectively.
+
+    Note: While the term [RP] is used in other contexts (e.g., X.509 and OAuth), an entity acting as an [RP] in one context is not necessarily an [RP] in others.
+
 : <dfn>Relying Party Identifier</dfn>
 : <dfn>RP ID</dfn>
 :: A Relying Party Identifier is derived from a <a>[RP]</a>'s web origin's hostname by computing the hostname's <a>eTLD+1</a>. 
-    
+
 : <dfn>Scoped Credential</dfn>
 :: Generically, a credential is data one entity presents to another in order to authenticate the former's identity [[RFC4949]].
 	A WebAuthn <em><a>scoped credential</a></em> is a <code>{ identifier, type }</code> pair identifying authentication
@@ -239,10 +245,6 @@ NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and
 : <dfn>[WAC]</dfn>
 :: See <a>Conforming User Agent</a>.
 
-: <dfn>[RP]</dfn>
-:: The entity whose web application utilizes the <a>Web Authentication API</a> to register and authenticate users. See
-	<a>Registration</a> and <a>Authentication</a>, respectively.
-