Update docs on send to match those of rhea (#40)

* Update docs on send to match those of rhea

* Improved messaging

* Remove Azure specific codes

lib/sender.ts

@@ -89,9 +89,13 @@ export class Sender extends Link {
 
   /**
    * Sends the message
-   * @param {Message | Buffer} msg The AMQP message to be sent.
-   * @param {Buffer | string} [tag] The optional tag that can be sent
-   * @param {number} [format] The format in which the message needs to be sent.
+   * @param {Message | Buffer} msg The message to be sent. For default AMQP format msg parameter
+   * should be of type Message interface. For a custom format, the msg parameter should be a Buffer
+   * and a valid value should be passed to the `format` argument.
+   * @param {Buffer | string} [tag] The message tag if any.
+   * @param {number} [format] The message format. Specify this if a message with custom format needs
+   * to be sent. `0` implies the standard AMQP 1.0 defined format. If no value is provided, then the
+   * given message is assumed to be of type Message interface and encoded appropriately.
    * @returns {Delivery} Delivery The delivery information about the sent message.
    */
   send(msg: Message | Buffer, tag?: Buffer | string, format?: number): Delivery {