Add documentation for Azure AD v2 (#257)

Author: kadikraman

docs/config-examples/azure-active-directory.md

@@ -1,6 +1,12 @@
 # Azure Active Directory
 
-Azure Active Directory [does not specify a revocation endpoint](https://docs.microsoft.com/en-us/azure/active-directory/active-directory-configurable-token-lifetimes#access-tokens) because the access token are not revokable. Therefore `revoke` functionality doesn't work.
+Azure Active directory has two OAuth endpoints - [v1 and v2](https://docs.microsoft.com/en-us/azure/active-directory/develop/azure-ad-endpoint-comparison). Ideally, you'd want to use v2, but it has [some limitations](https://docs.microsoft.com/en-us/azure/active-directory/develop/azure-ad-endpoint-comparison#limitations), e.g. if your application relies on SAML, you'll have to use v1.
+
+## V1
+
+The main difference between v1 and v2 is that v2 uses _resources_ and v2 uses _scopes_ for access management.
+
+V1 [does not specify a revocation endpoint](https://docs.microsoft.com/en-us/azure/active-directory/active-directory-configurable-token-lifetimes#access-tokens) because the access token are not revokable. Therefore `revoke` functionality doesn't work.
 
 See the [Azure docs on requesting an access token](https://docs.microsoft.com/en-us/azure/active-directory/develop/active-directory-protocols-oauth-code#request-an-authorization-code) for more info on additional parameters.
 
@@ -15,7 +21,6 @@ const config = {
   issuer: 'https://login.microsoftonline.com/your-tenant-id',
   clientId: 'your-client-id',
   redirectUrl: 'urn:ietf:wg:oauth:2.0:oob',
-  scopes: [], // ignored by Azure AD
   additionalParameters: {
     resource: 'your-resource'
   }
@@ -29,3 +34,24 @@ const refreshedState = await refresh(config, {
   refreshToken: authState.refreshToken,
 });
 ```
+
+## V2
+
+The V2 endpoint follows the standard OAuth protocol with scopes. Detailed documentation [here](https://docs.microsoft.com/en-us/azure/active-directory/develop/v2-overview).
+
+```js
+const config = {
+  issuer: 'https://login.microsoftonline.com/your-tenant-id/v2.0',
+  clientId: 'your-client-id',
+  redirectUrl: 'urn:ietf:wg:oauth:2.0:oob',
+  scopes: ['openid', 'profile', 'email', 'offline_access']
+};
+
+// Log in to get an authentication token
+const authState = await authorize(config);
+
+// Refresh token
+const refreshedState = await refresh(config, {
+  refreshToken: authState.refreshToken,
+});
+```