Add some words to 313 to explain to not archive stanzas not accepted for delivery

xep-0313.xml

@@ -431,13 +431,14 @@
   <section2 topic='What To Store'>
   	<p>Different entities will have different requirements for which data are stored, as might different deployments. This section provides general rules within which a server will act. While there may be local policy restrictions that prevent archiving of some aspects discussed here, this is a RECOMMENDED baseline. A server MAY implement any subset of possible archives for JIDs it controls (although it MUST advertise support only for those JIDs that support it).</p>
 	<p>No requirements are placed on how a server implements its storage beyond that it has to store data sufficient to be able to comply with this document. When this document describes storage requirements (e.g. MUST NOT store more than one copy...), it refers to what would appear to have been stored in order to satisfy the query.</p>
+    <p>If an entity (user's server, MUC room, pubsub node, ...) rejects an incoming message (such as from an occupant not allowed to send messages to the room, a user not authorized to publish to a pubsub node, a contact blocked by the user etc.) that message should not appear in the archive for the entity that rejected it - the archive should represent what logical entities (MUC occupants, users, pubsub subscribers...) would have received, and so only contain messages accepted for delivery to such entities.</p>
   	<section3 topic="User Archives">
   		<p>A user archive is anticipated to provide the user with the ability to access their prior conversations. To this end, a server SHOULD include in a user archive all of the messages a user sends or receives of type 'normal' or 'chat' that contain a &lt;body&gt; element. A server SHOULD also include messages of type 'groupchat' that have a &lt;body&gt;, but where such history is accessible through another method (e.g. through an archive on the MUC JID), a server MAY exclude these from the archive. A server MAY include additional non-conversation messages. A server MAY include messages of type 'headline', but this is not generally suggested.</p>
   		<p>At a minimum, the server MUST store the &lt;body&gt; elements of a stanza. It is suggested that other elements that are used in a given deployment to supplement conversations (e.g. XHTML-IM payloads) are also stored. Other elements MAY be stored.</p>
   		<p>If a server supports mechanisms that multiply copies of a stanza (e.g. Carbons, or forking a stanza to a bare JID), it MUST store such a staza within a given archive only once, irrespective of multiple connected clients receiving copies</p>
   	</section3>
   	<section3 topic="MUC Archives">
-  		<p>A MUC archives allows a user to view the conversation within a room. All messages sent to the room that contain a &lt;body&gt; element SHOULD be stored, as should subject change stanzas.</p>
+  		<p>A MUC archives allows a user to view the conversation within a room. All messages sent to the room that contain a &lt;body&gt; element SHOULD be stored, as should subject change stanzas, apart from those messages that the room rejects.</p>
   		<p>A MUC archive MUST store each message only once (not, for example, every copy sent out to an occupant).</p>
   		<p>When sending out the archives to a requesting client, the 'to' of the forwarded stanza MUST be empty, and the 'from' MUST be the occupant JID of the sender of the archived message.</p>
           <p>A MUC archive MUST NOT include 'private message' results (those sent directly between occupants, not shared in the room) in the results</p>