More documentation with samples in typescript

There's this [walkthrough](https://docs.aws.amazon.com/cloudformation-cli/latest/userguide/resource-type-walkthrough.html) but it's using *java* as the language, and it's not very easy to understand.

From the documentation perspective, I don't understand how to call `dynamodb` from the handlers for example. It looks like I need to use the `SessionProxy`, but it's not documented how to get a hold of *dynamodb* aws client.
In the *init* example:
```
// Example:
try {
if (session instanceof SessionProxy) {
const client = session.client('S3');
}
```
1. Where's the documentation of which *string* should I pass in the `.client([string])` to get dynamodb, stepfunction (or others) clients?

2. Even after I run `npm install` to install the dependencies, VSCode still does not find `@amazon-web-services-cloudformation/cloudformation-cli-typescript-lib`


3. Also, do I need to implement all "create, update, list, read..." operations? I was looking for to implement only *create*, *update* and *delete*.

Examinez le guide lié sur les types de ressources AWS CloudFormation ainsi que l’exemple d’initialisation TypeScript utilisant SessionProxy. Vérifiez comment les clients de service tels que DynamoDB sont nommés et obtenus, pourquoi VSCode ne trouve pas la bibliothèque TypeScript installée et quels handlers sont requis ; le travail est considéré comme terminé lorsque le guide répond à ces questions avec des exemples fonctionnels.

Rédigé par le modèle d'indexation à partir du texte de l'issue.