Provide Microsoft.Extensions.Http.Polly package README

src/HttpClientFactory/Polly/src/PACKAGE.md

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+## About
+
+`Microsoft.Extensions.Http.Polly` integrates `IHttpClientFactory` with the [Polly](https://github.com/App-vNext/Polly) library to provide comprehensive resilience and transient fault-handling. It allows developers to express policies such as Retry, Circuit Breaker, Timeout, Bulkhead Isolation, and Fallback in a fluent and thread-safe manner.
+
+> [!NOTE]
+> This package is deprecated. Please use either [`Microsoft.Extensions.Resilience`](https://www.nuget.org/packages/Microsoft.Extensions.Resilience) or [`Microsoft.Extensions.Http.Resilience`](https://www.nuget.org/packages/Microsoft.Extensions.Http.Resilience) instead.
+
+## How to Use
+
+To use `Microsoft.Extensions.Http.Polly`, follow these steps:
+
+### Installation
+
+```shell
+dotnet add package Microsoft.Extensions.Http.Polly
+```
+
+### Usage
+
+#### Handle transient faults
+
+`AddTransientHttpErrorPolicy` can be used define a policy that handles transient errors:
+
+```csharp
+builder.Services.AddHttpClient("PollyWaitAndRetry")
+    .AddTransientHttpErrorPolicy(policyBuilder =>
+        policyBuilder.WaitAndRetryAsync(
+            retryCount: 3,
+            retryNumber => TimeSpan.FromMilliseconds(600)));
+```
+
+In the preceding example, failed requests are retried up to three times with a delay of 600 ms between attempts.
+
+#### Dynamically select policies
+
+To dynamically inspect a request and decide which policy apply, use the `AddPolicyHandler` extension method:
+
+```csharp
+var timeoutPolicy = Policy.TimeoutAsync<HttpResponseMessage>(
+    TimeSpan.FromSeconds(10));
+var longTimeoutPolicy = Policy.TimeoutAsync<HttpResponseMessage>(
+    TimeSpan.FromSeconds(30));
+
+builder.Services.AddHttpClient("PollyDynamic")
+    .AddPolicyHandler(httpRequestMessage =>
+        httpRequestMessage.Method == HttpMethod.Get
+            ? timeoutPolicy
+            : longTimeoutPolicy);
+```
+
+In this example, if the outgoing request is an HTTP GET, a 10-second timeout is applied. For any other HTTP method, a 30-second timeout is used.
+
+## Main Types
+
+The main types provided by this package are:
+
+* `PollyHttpClientBuilderExtensions`: Provides extension methods for configuring `PolicyHttpMessageHandler` message handlers as part of an `HttpClient` message handler pipeline
+* `PolicyHttpMessageHandler`: A `DelegatingHandler` implementation that executes request processing surrounded by a `Polly.Policy`
+* `PollyServiceCollectionExtensions`: Provides convenience extension methods to register `Polly.Registry.IPolicyRegistry<string>` and `Polly.Registry.IReadOnlyPolicyRegistry<string>` in a service collection
+* `HttpRequestMessageExtensions`: Provides extension methods for `HttpRequestMessage` Polly integration
+
+## Additional Documentation
+
+For additional documentation and examples, refer to the [official documentation](https://learn.microsoft.com/aspnet/core/fundamentals/http-requests?view#use-polly-based-handlers) on using Polly-based handlers in ASP.NET Core.
+
+## Feedback &amp; Contributing
+
+`Microsoft.Extensions.Http.Polly` is released as open-source under the [MIT license](https://licenses.nuget.org/MIT). Bug reports and contributions are welcome at [the GitHub repository](https://github.com/dotnet/aspnetcore).