Update credential chains doc for v1.16.0 release (#48547)

* Update credential chains doc for v1.16.0 release

* Replace image

Author: scottaddie

docs/azure/sdk/authentication/credential-chains.md

@@ -112,8 +112,7 @@ When a value of `dev` is used, the chain looks as follows:
 
 :::image type="content" source="../media/mermaidjs/default-azure-credential-environment-variable-development.svg" alt-text="DefaultAzureCredential with AZURE_TOKEN_CREDENTIALS set to 'dev'":::
 
-> [!IMPORTANT]
-> The `AZURE_TOKEN_CREDENTIALS` environment variable is supported in `Azure.Identity` package versions 1.14.0 and later.
+To ensure the environment variable is defined and set to a supported string, use constructor overload <xref:Azure.Identity.DefaultAzureCredential.%23ctor(System.String,Azure.Identity.DefaultAzureCredentialOptions)?displayProperty=name>.
 
 #### Use a specific credential
 
@@ -133,6 +132,8 @@ To exclude all credentials except for one, set environment variable `AZURE_TOKEN
 > [!IMPORTANT]
 > The `AZURE_TOKEN_CREDENTIALS` environment variable supports individual credential names in `Azure.Identity` package versions 1.15.0 and later.
 
+To ensure the environment variable is defined and set to a supported string, use constructor overload <xref:Azure.Identity.DefaultAzureCredential.%23ctor(System.String,Azure.Identity.DefaultAzureCredentialOptions)?displayProperty=name>.
+
 ## ChainedTokenCredential overview
 
 [ChainedTokenCredential](/dotnet/api/azure.identity.chainedtokencredential?view=azure-dotnet&preserve-view=true) is an empty chain to which you add credentials to suit your app's needs. For example:

docs/azure/sdk/media/mermaidjs/default-azure-credential-environment-variable-development.md

@@ -1,6 +1,6 @@
 ---
 ms.topic: include
-ms.date: 08/13/2025
+ms.date: 09/16/2025
 ---
 
 ```mermaid
@@ -28,7 +28,8 @@ flowchart LR;
     E(Visual Studio Code):::developer -->
     F(Azure CLI):::developer -->
     G(Azure PowerShell):::developer -->
-    H(Azure Developer CLI):::developer;
+    H(Azure Developer CLI):::developer -->
+    J(Broker):::developer;
 
     %% Define styles for credential type boxes
     classDef developer fill:#F5AF6F, stroke:#EB7C39, stroke-width:2px;