Improve mgmt readme for identity support (#14921)

common/tools/add-identity-mgmt-lib.js

@@ -62,26 +62,37 @@ This package contains an isomorphic SDK (runs both in node.js and in browsers) f
 - Node.js version 8.x.x or higher
 - Browser JavaScript
 
+### Prerequisites
+
+You must have an [Azure subscription](https://azure.microsoft.com/free/).
+
 ### How to install
 
 To use this SDK in your project, you will need to install two packages.
 - \`${pkgName}\` that contains the client.
-- \`@azure/identity\` that contains different credentials for you to authenticate the client using Azure Active Directory.
+- \`@azure/identity\` that provides different mechanisms for the client to authenticate your requests using Azure Active Directory.
 
-Install both packages using the below commands.
+Install both packages using the below command:
 \`\`\`bash
-npm install ${pkgName}
-npm install @azure/identity
+npm install --save ${pkgName} @azure/identity
 \`\`\`
-Please note that while the credentials from the older [\`@azure/ms-rest-nodeauth\`](https://www.npmjs.com/package/@azure/ms-rest-nodeauth) and [\`@azure/ms-rest-browserauth\`](https://www.npmjs.com/package/@azure/ms-rest-browserauth) packages are still supported, these packages are in maintenance mode receiving critical bug fixes, but no new features.
-We strongly encourage you to use the credentials from \`@azure/identity\` where the latest versions of Azure Active Directory and MSAL APIs are used and more authentication options are provided.
+
+> **Note**: You may have used either \`@azure/ms-rest-nodeauth\` or \`@azure/ms-rest-browserauth\` in the past. These packages are in maintenance mode receiving critical bug fixes, but no new features.
+We strongly encourage you to upgrade to \`@azure/identity\` which uses the latest versions of Azure Active Directory and MSAL APIs and provides more authentication options.
 
 ### How to use
 
-There are multiple credentials available in the \`@azure/identity\` package to suit your different authentication needs.
-Read about them in detail in [readme for @azure/identity package](https://www.npmjs.com/package/@azure/identity).
-To get started you can use the [DefaultAzureCredential](https://github.com/Azure/azure-sdk-for-js/blob/master/sdk/identity/identity/README.md#defaultazurecredential) which tries different credentials internally until one of them succeeds.
-Most of the credentials would require you to [create an Azure App Registration](https://docs.microsoft.com/en-us/azure/active-directory/develop/app-objects-and-service-principals#application-registration) first.
+- If you are writing a client side browser application, 
+  - See [Single-page application: App registration guide](https://docs.microsoft.com/azure/active-directory/develop/scenario-spa-app-registration) to configure your app registration for the browser.
+  - Note down the client Id from the previous step and use it in the browser sample below.
+- If you are writing a server side application, 
+    - [Select a credential from \`@azure/identity\` based on the authentication method of your choice](https://aka.ms/azsdk/js/identity/examples)
+    - Complete the set up steps required by the credential if any.
+    - Use the credential you picked in the place of \`DefaultAzureCredential\` in the Node.js sample below.
+- Pass the credential and the Azure subscription id to instantiate the client. 
+- Once the client is created, explore the operations on it either in your favorite editor or in our [API reference documentation](https://docs.microsoft.com/javascript/api) to get started.
+
+
 #### nodejs - Authentication, client creation, and ${operationHeader} as an example written in JavaScript.
 
 ##### Sample code
@@ -91,7 +102,7 @@ const { DefaultAzureCredential } = require("@azure/identity");
 const { ${clientName} } = require("${pkgName}");
 const subscriptionId = process.env["AZURE_SUBSCRIPTION_ID"];
 
-// Create credentials using the \`@azure/identity\` package.
+// Use \`DefaultAzureCredential\` or any other credential of your choice based on https://aka.ms/azsdk/js/identity/examples
 // Please note that you can also use credentials from the \`@azure/ms-rest-nodeauth\` package instead.
 const creds = new DefaultAzureCredential();
 const client = new ${clientName}(creds, subscriptionId);
@@ -109,7 +120,8 @@ client.${operation}(resourceGroupName, resourceName).then((result) => {
 #### browser - Authentication, client creation, and ${operationHeader} as an example written in JavaScript.
 
 In browser applications, we recommend using the \`InteractiveBrowserCredential\` that interactively authenticates using the default system browser.
-It is necessary to [create an Azure App Registration](https://docs.microsoft.com/azure/active-directory/develop/scenario-spa-app-registration) in the portal for your web application first.
+  - See [Single-page application: App registration guide](https://docs.microsoft.com/azure/active-directory/develop/scenario-spa-app-registration) to configure your app registration for the browser.
+  - Note down the client Id from the previous step and use it in the browser sample below.
 
 ##### Sample code