Add sample configuration for resource lists.

On review /r/3977, it was recommended to note in the
sample configuration about the size limitation for
resource lists. However, since there was no section in
the sample configuration at all for resource list
subscriptions, I decided to make a separate commit
where I have added the necessary sample configuration
as well as the size limitation warning.
........

Merged revisions 422853 from http://svn.asterisk.org/svn/asterisk/branches/13


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@422854 65c4cc65-6c06-0410-ace0-fbb531ad65f3

configs/samples/pjsip.conf.sample

@@ -428,6 +428,54 @@
 ;permit=209.16.236.0/24, !209.16.236.12/32
 
 
+;============EXAMPLE RLS CONFIGURATION==========================================
+;
+;Asterisk provides support for RFC 4662 Resource List Subscriptions. This allows
+;for an endpoint to, through a single subscription, subscribe to the states of
+;multiple resources. Resource lists are configured in pjsip.conf using the
+;resource_list configuration object. Below is an example of a resource list that
+;allows an endpoint to subscribe to the presence of alice, bob, and carol.
+
+;[my_list]
+;type=resource_list
+;list_item=alice
+;list_item=bob
+;list_item=carol
+;event=presence
+
+;The "event" option in the resource list corresponds to the SIP event-package
+;that the subscribed resources belong to. A resource list can only provide states
+;for resources that belong to the same event-package. This means that you cannot
+;create a list that is a combination of presence and message-summary resources,
+;for instance. Any event-package that Asterisk supports can be used in a resource
+;list (presence, dialog, and message-summary). Whenever support for a new event-
+;package is added to Asterisk, support for that event-package in resource lists
+;will automatically be supported.
+
+;The "list_item" options indicate the names of resources to subscribe to. The
+;way these are interpreted is event-package specific. For instance, with presence
+;list_items, hints in the dialplan are looked up. With message-summary list_items,
+;mailboxes are looked up using your installed voicemail provider (app_voicemail
+;by default).
+
+;In addition to the options presented in the above configuration, there are two
+;more configuration options that can be set.
+; * full_state: dictates whether Asterisk should always send the states of
+;   all resources in the list at once. Defaults to "no". You should only set
+;   this to "yes" if you are interoperating with an endpoint that does not
+;   behave correctly when partial state notifications are sent to it.
+; * notification_batch_interval: By default, Asterisk will send a NOTIFY request
+;   immediately when a resource changes state. This option causes Asterisk to
+;   start batching resource state changes for the specified number of milliseconds
+;   after a resource changes states. This way, if multiple resources change state
+;   within a brief interval, Asterisk can send a single NOTIFY request with all
+;   of the state changes reflected in it.
+
+;There is a limitation to the size of resource lists in Asterisk. If a constructed
+;notification from Asterisk will exceed 64000 bytes, then the message is deemed
+;too large to send. If you find that you are seeing error messages about SIP
+;NOTIFY requests being too large to send, consider breaking your lists into
+;sub-lists.
 
 ; MODULE PROVIDING BELOW SECTION(S): res_pjsip
 ;==========================ENDPOINT SECTION OPTIONS=========================