Update doc and add variable in bicep file

Author: Shreyas-Microsoft

docs/ConfigureAppAuthentication.md

@@ -76,6 +76,8 @@ We will add Microsoft Entra ID as an authentication provider to API and Web Appl
 
    - Select **Overview** in the left menu. Copy the Client Id, then paste it in some temporary place.
      The copied text will be used for Web Application Environment variable - **APP_WEB_CLIENT_ID**.
+   - Also copy the Tenant Id, then paste it in some temporary place.
+     The copied text will be used for Web Application Environment variable - **APP_MSAL_AUTH_AUTHORITY**.
      ![configure_app_registration_web_10](./images/configure_app_registration_web_10.png)
 
 ## Step 3: Configure Application Registration - API Application
@@ -115,9 +117,10 @@ Now, we will edit and deploy the Web Application Container with updated Environm
 | REACT_APP_MSAL_AUTH_CLIENTID     | In Step 2, Client Id for Web                 |
 | REACT_APP_WEB_SCOPE              | In Step 2, Scope Name                        |
 | REACT_APP_API_SCOPE              | In Step 3, Scope Name                        |
-| REACT_APP_MSAL_AUTH_AUTHORITY    | https://login.microsoftonline.com/'TenantId' |
+| REACT_APP_MSAL_AUTH_AUTHORITY    | https://login.microsoftonline.com/'TenantId' <br/>*Note: Replace 'TenantId' with the Tenant Id copied in Step 2, point 4* |
 | REACT_APP_MSAL_POST_REDIRECT_URL | /                                            |
 | REACT_APP_MSAL_REDIRECT_URL      | /                                            |
+| ENABLE_AUTH                      | true                                         |
 
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docs/images/configure_app_registration_web_10.png

@@ -1084,6 +1084,14 @@ module containerAppFrontend 'br/public:avm/res/app/container-app:0.18.1' = {
             name: 'APP_ENV'
             value: 'prod'
           }
+          {
+            name: 'REACT_APP_MSAL_POST_REDIRECT_URL'
+            value: '/'
+          }
+          {
+            name: 'REACT_APP_MSAL_REDIRECT_URL'
+            value: '/'
+          }
         ]
         resources: {
           cpu: '1'