V0.6.6 update (#18)

* content updates for v06.6

* updated release notes

markdown/docs/webhooks/message.md

@@ -0,0 +1,42 @@
+# message
+> New in v0.6.6 (beta)
+The `message` verb is used to send an SMS via a carrier using the [SMPP](https://smpp.org/) protocol.  It requires that you have added a BYOC carrier configured that supports SMS.
+
+> You can also send SMS via the REST API.  [See here](https://api.jambonz.org/#54f1de57-3740-49f3-bd29-e68541d63dc3) for more details on that.
+
+```json
+{
+  "verb": "message",
+  "to": "15083084809",
+  "from": "16173334567",
+  "text": "Your one-time passcode is 1234",
+  "actionHook": "/sms/action"
+}
+```
+
+You can use the following options in the `message` verb:
+
+| option        | description | required  |
+| ------------- |-------------| -----|
+| from | sending number | yes |
+| to | destination number | yes |
+| text | text message to send | yes |
+| carrier | name of BYOC carrier to use (useful only when you have multiple carriers configured with SMPP support, otherwise leave out) | no |
+| actionHook | A webhook that is called when the message verb completes | no |
+
+<h5 id="message-action-properties">actionHook properties</h5>
+
+The actionHook that is invoked when the `message` command completes will include the following properties:
+
+| property name  | description | 
+| ------------- |-------------|
+| message_sid | the unique identifier for the message assigned by jambonz |
+| message_status | the final status of the message attempt; will be one of:<ul><li>- success</li><li>- failure</li><li>- no carriers</li><li>- smpp configuration error, or</li><li>- system error</li></ul>|
+| message_failure_reason | in the case of message_status 'failure', this will contain detail describing why the outbound smpp request failed|
+| carrier | the name of the carrier selected to send the SMS|
+| carrier_message_id | the message identifier assigned by the carrier for this SMS|
+
+<p class="flex">
+<a href="/docs/webhooks/listen">Prev: listen</a>
+<a href="/docs/webhooks/pause">Next: pause</a>
+</p>