add undocumented options to readme (#374)

Author: graebm

README.md

@@ -359,14 +359,18 @@ follows:
   * `minimumConnectionTimeMs`: the minimum time in milliseconds that a connection must be maintained in order to be considered stable (default 20000)
   * `protocol`: the connection type, either 'mqtts' (default), 'wss' (WebSocket/TLS), or 'wss-custom-auth' (WebSocket/TLS with custom authentication).  Note that when set to 'wss', values must be provided for the Access Key ID and Secret Key in either the following options or in environment variables as specified in [WebSocket Configuration](#websockets). When set to 'wss-custom-auth', valid headers must be provided as specified in [Custom Auth](#custom-auth)
   * `websocketOptions`: if `protocol` is set to 'wss', you can use this parameter to pass additional options to the underlying WebSocket object; these options are documented [here](https://github.com/websockets/ws/blob/master/doc/ws.md#class-wswebsocket).
-  * `filename`: used to load credentials from the file different than the default localtion when `protocol` is set to 'wss'. Default value is '~/.aws/credentials'
+  * `filename`: used to load credentials from the file different than the default location when `protocol` is set to 'wss'. Default value is '~/.aws/credentials'
   * `profile`: used to specify which credential profile to be used when `protocol` is set to 'wss'.  Default value is 'default'
   * `accessKeyId`: used to specify the Access Key ID when `protocol` is set to 'wss'.  Overrides the environment variable `AWS_ACCESS_KEY_ID` and `AWS_ACCESS_KEY_ID` from `filename` if set.
   * `secretKey`: used to specify the Secret Key when `protocol` is set to 'wss'.  Overrides the environment variable `AWS_SECRET_ACCESS_KEY`and `AWS_SECRET_ACCESS_KEY`  from `filename` if set.
   * `sessionToken`: (required when authenticating via Cognito, optional otherwise) used to specify the Session Token when `protocol` is set to 'wss'.  Overrides the environment variable `AWS_SESSION_TOKEN` if set.
+  * `region`: used to specify AWS account region (e.g. 'us-east-1') when `protocol` is set to `wss`. If undefined, a value is derived from `host`.
   * `customAuthHeaders`: used to specify your custom authorization headers when `protocol` is set to 'wss-custom-auth'. The fields 'X-Amz-CustomAuthorizer-Name', 'X-Amz-CustomAuthorizer-Signature', and the field for your token name are required.
+  * `servername`: used for SNI. If undefined, a value is derived from `host`.
+  * `port`: used to specify which port to connect to. If undefined, 443 or 8883 will be chosen depending on `protocol`.
   * `keepalive`: used to specify the time interval for each ping request. Default is set to 300 seconds to connect to AWS IoT.
   * `enableMetrics`: used to report SDK version usage metrics. It is set to true by default. To disable metrics collection, set value to false.
+  * `debug`: set to 'true' for verbose logging (default 'false').
 
 All certificates and keys must be in PEM format.