Add missing credentials to Identity README (Azure#2701)

* Add missing credentials to Identity README

* Update heading

* More edits

* Update sdk/identity/azure_identity/README.md

Co-authored-by: Copilot <[email protected]>

* Replace class with struct

* Add structs to dictionary

* React to feedback

* Update dictionary

---------

Co-authored-by: Copilot <[email protected]>

Author: scottaddie

sdk/identity/azure_identity/README.md

@@ -33,9 +33,9 @@ When no default browser is available, `az login` uses the device code authentica
 
 ### Credentials
 
-A credential is a class that contains or can obtain the data needed for a service client to authenticate requests. Service clients across the Azure SDK accept a credential instance when they're constructed, and use that credential to authenticate requests.
+A credential is a struct that contains or can obtain the data needed for a service client to authenticate requests. Service clients across the Azure SDK accept a credential instance when they're constructed, and use that credential to authenticate requests.
 
-The Azure Identity library focuses on OAuth authentication with Microsoft Entra ID. It offers various credential classes capable of acquiring a Microsoft Entra access token. See the [Credential classes](#credential-classes "Credential classes") section for a list of this library's credential classes.
+The Azure Identity library focuses on OAuth authentication with Microsoft Entra ID. It offers various credentials capable of acquiring a Microsoft Entra access token. See the [Credential structures](#credential-structures "Credential structures") section for a list of this library's credentials.
 
 ### DefaultAzureCredential
 
@@ -55,7 +55,7 @@ The following examples are provided:
 
 ### Authenticate with `DefaultAzureCredential`
 
-More details on configuring your environment to use `DefaultAzureCredential` can be found in the class's [reference documentation][default_cred_ref].
+More details on configuring your environment to use `DefaultAzureCredential` can be found in the struct's [reference documentation][default_cred_ref].
 
 This example demonstrates authenticating the `SecretClient` from the [azure_security_keyvault_secrets] crate using `DefaultAzureCredential`.
 
@@ -122,7 +122,7 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
 
 ```
 
-## Credential classes
+## Credential structures
 
 ### Credential chains
 
@@ -134,19 +134,24 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
 
 |Credential|Usage
 |-|-
+|[`ManagedIdentityCredential`][managed_id_cred_ref]| Authenticates the managed identity of an Azure resource.
 |[`WorkloadIdentityCredential`][workload_id_cred_ref]| Supports [Microsoft Entra Workload ID](https://learn.microsoft.com/azure/aks/workload-identity-overview) on Kubernetes.
 
 ### Authenticate service principals
 
 |Credential|Usage|Reference
 |-|-|-
+|[`AzurePipelinesCredential`][az_pipelines_cred_ref]| Supports [Microsoft Entra Workload ID](https://learn.microsoft.com/azure/devops/pipelines/release/configure-workload-identity?view=azure-devops) on Azure Pipelines. |
+|[`ClientAssertionCredential`][assert_cred_ref]| Authenticates a service principal using a signed client assertion. | [Service principal authentication](https://learn.microsoft.com/entra/identity-platform/app-objects-and-service-principals)
 |[`ClientCertificateCredential`][cert_cred_ref]| Authenticates a service principal using a certificate. | [Service principal authentication](https://learn.microsoft.com/entra/identity-platform/app-objects-and-service-principals)
+|[`ClientSecretCredential`][secret_cred_ref]| Authenticates a service principal using a secret. | [Service principal authentication](https://learn.microsoft.com/entra/identity-platform/app-objects-and-service-principals)
 
 ### Authenticate via development tools
 
 |Credential|Usage|Reference
 |-|-|-
 |[`AzureCliCredential`][cli_cred_ref]| Authenticates in a development environment with the Azure CLI. | [Azure CLI authentication](https://learn.microsoft.com/cli/azure/authenticate-azure-cli)
+|[`AzureDeveloperCliCredential`][azd_cred_ref]| Authenticates in a development environment with the Azure Developer CLI. | [Azure Developer CLI reference](https://learn.microsoft.com/azure/developer/azure-developer-cli/reference)
 
 ## Next steps
 
@@ -167,15 +172,20 @@ When you submit a pull request, a CLA-bot will automatically determine whether y
 This project has adopted the [Microsoft Open Source Code of Conduct](https://opensource.microsoft.com/codeofconduct/). For more information, see the [Code of Conduct FAQ](https://opensource.microsoft.com/codeofconduct/faq/) or contact [[email protected]](mailto:[email protected]) with any additional questions or comments.
 
 <!-- LINKS -->
+[assert_cred_ref]: https://docs.rs/azure_identity/latest/azure_identity/struct.ClientAssertionCredential.html
+[az_pipelines_cred_ref]: https://docs.rs/azure_identity/latest/azure_identity/struct.AzurePipelinesCredential.html
+[azd_cred_ref]: https://docs.rs/azure_identity/latest/azure_identity/struct.AzureDeveloperCliCredential.html
 [Azure CLI]: https://learn.microsoft.com/cli/azure
 [azure_security_keyvault_secrets]: https://github.com/Azure/azure-sdk-for-rust/tree/main/sdk/keyvault/azure_security_keyvault_secrets
 [Azure subscription]: https://azure.microsoft.com/free/
 [cert_cred_ref]: https://docs.rs/azure_identity/latest/azure_identity/struct.ClientCertificateCredential.html
 [cli_cred_ref]: https://docs.rs/azure_identity/latest/azure_identity/struct.AzureCliCredential.html
 [default_cred_ref]: https://docs.rs/azure_identity/latest/azure_identity/struct.DefaultAzureCredential.html
+[managed_id_cred_ref]: https://docs.rs/azure_identity/latest/azure_identity/struct.ManagedIdentityCredential.html
 [Microsoft Entra ID documentation]: https://learn.microsoft.com/entra/identity/
 [API reference documentation]: https://docs.rs/azure_identity/latest/azure_identity/
 [Package (crates.io)]: https://crates.io/crates/azure_identity
+[secret_cred_ref]: https://docs.rs/azure_identity/latest/azure_identity/struct.ClientSecretCredential.html
 [Source code]: https://github.com/Azure/azure-sdk-for-rust/tree/main/sdk/identity/azure_identity
 [token_cred_ref]: https://docs.rs/azure_core/latest/azure_core/credentials/trait.TokenCredential.html
 [workload_id_cred_ref]: https://docs.rs/azure_identity/latest/azure_identity/struct.WorkloadIdentityCredential.html