docs: update readme

README.md

@@ -2,14 +2,16 @@
 
 This is a CDK construct that creates an AWS IoT Core Thing with a certificate and policy using [aws-sdk-js-v3](https://github.com/aws/aws-sdk-js-v3).
 
+![elements](./images/iot.png)
+
 Cloudformation does not support creating a certificate for an IoT Thing, so this construct uses the AWS SDK to create a certificate and attach it to the Thing.
 
 This construct is a modified version of this excellent [construct (cdk-iot-core-certificate)](https://github.com/devops-at-home/cdk-iot-core-certificates) to work with aws-sdk-js-v3.
 
 ## Installation
 
 ```bash
-npm i cdk-iot-core-certificate-v3
+npm i cdk-iot-core-certificates-v3
 ```
 
 ## Usage
@@ -18,8 +20,11 @@ npm i cdk-iot-core-certificate-v3
 import { ThingWithCert } from 'cdk-iot-core-certificate-v3';
 
 const thing = new ThingWithCert(this, 'MyThing', {
+  // The name of the thing
   thingName: 'MyThing',
+  // Whether to save the certificate and private key to the SSM Parameter Store
   saveToParamStore: true,
+  // The prefix to use for the SSM Parameter Store parameters
   paramPrefix: 'test',
 });