docs: AMI documentation fixes.

Most of this patch is adding missing PJSIP-related event
documentation, but the one functional change was adding a sorcery
to-string handler for endpoint's `redirect_method` which was not
showing up in the AMI event details or `pjsip show endpoint
<endpoint>` output.

The rest of the changes are summarized below:

* app_agent_pool.c: Typo fix Epoche -> Epoch.
* stasis_bridges.c: Add missing AttendedTransfer properties.
* stasis_channels.c: Add missing AgentLogoff properties.
* pjsip_manager.xml:
  - Add missing AorList properties.
  - Add missing AorDetail properties.
  - Add missing ContactList properties.
  - Add missing ContactStatusDetail properties.
  - Add missing EventDetail properties.
  - Add missing AuthList properties.
  - Add missing AuthDetail properties.
  - Add missing TransportDetail properties.
  - Add missing EndpointList properties.
  - Add missing IdentifyDetail properties.
* res_pjsip_registrar.c: Add missing InboundRegistrationDetail documentation.
* res_pjsip_pubsub.c:
  - Add missing ResourceListDetail documentation.
  - Add missing InboundSubscriptionDetail documentation.
  - Add missing OutboundSubscriptionDetail documentation.
* res_pjsip_outbound_registration.c: Add missing OutboundRegistrationDetail documentation.

main/stasis_bridges.c

@@ -122,6 +122,7 @@
 					<note><para>This header is only present when <replaceable>DestType</replaceable> is <literal>Threeway</literal></para></note>
 				</parameter>
 				<channel_snapshot prefix="Transferee" />
+				<channel_snapshot prefix="TransferTarget" />
 			</syntax>
 			<description>
 				<para>The headers in this event attempt to describe all the major details of the attended transfer. The two transferer channels