Update README with instructions to use aws-sdk-js-codemod (#16)

Author: trivikr

.changeset/many-jobs-doubt.md

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+---
+"aws-sdk-js-codemod": patch
+---
+
+Update README with instructions to use aws-sdk-js-codemod

README.md

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 # aws-sdk-js-codemod
-Codemod scripts for AWS SDK for JavaScript
+
+This repository contains a collection of codemod scripts for use with
+[JSCodeshift][jscodeshift] that help update [AWS SDK for JavaScript][aws-sdk-js]
+APIs.
+
+The `aws-sdk-js-codemod` CLI is a lightweight wrapper over jscodeshift.
+It processes `--help`, `--version` and `--transform` options before passing them
+downstream.
+
+You can provide names of the custom transforms instead of a local path or url:
+
+     v2-to-v3  Converts AWS SDK for JavaScript APIs in a Javascript/TypeScript
+               codebase from version 2 (v2) to version 3 (v3).
+
+## Prerequisites
+
+To use aws-sdk-js-codemod, please install [Node.js][install-nodejs].
+
+## Usage
+
+- Optionally execute dry-run for the transform, and print transformed files on stdout:
+  ```console
+  npx aws-sdk-js-codemod --dry --print -t v2-to-v3 PATH...
+  ```
+- Run transform:
+  ```console
+  npx aws-sdk-js-codemod -t v2-to-v3 PATH...
+  ```
+
+## Example
+
+```console
+$ cat example.ts
+import AWS from "aws-sdk";
+
+const region = "us-west-2";
+const client = new AWS.DynamoDB({ region });
+client.listTables({}, (err, data) => {
+  if (err) console.log(err, err.stack);
+  else console.log(data);
+});
+
+$ npx aws-sdk-js-codemod -t v2-to-v3 example.ts
+
+$ cat example.ts
+import AWS from "aws-sdk";
+
+import { DynamoDB } from "@aws-sdk/client-dynamodb";
+
+const region = "us-west-2";
+const client = new DynamoDB({ region });
+client.listTables({}, (err, data) => {
+  if (err) console.log(err, err.stack);
+  else console.log(data);
+});
+
+```
+
+[aws-sdk-js]: https://aws.amazon.com/sdk-for-javascript/
+[install-nodejs]: https://nodejs.dev/learn/how-to-install-nodejs
+[jscodeshift]: https://github.com/facebook/jscodeshift