feat: add package readme

Author: sliedig

libraries/src/AWS.Lambda.Powertools.Parameters/README.md

@@ -0,0 +1,51 @@
+# AWS.Lambda.Powertools.Parameters
+
+The Parameters utility provides high-level functionality to retrieve one or multiple parameter values from [AWS Systems Manager Parameter Store](https://docs.aws.amazon.com/systems-manager/latest/userguide/systems-manager-parameter-store.html), [AWS Secrets Manager](https://aws.amazon.com/secrets-manager/), or [Amazon DynamoDB](https://aws.amazon.com/dynamodb/). Or bring your own providers.
+
+## Key features
+
+* Retrieve one or multiple parameters from the underlying provider
+* Cache parameter values for a given amount of time (defaults to 5 seconds)
+* Transform parameter values from JSON or base 64 encoded strings
+* Bring your own parameter store provider
+
+## Read the docs
+
+For a full list of features go to [awslabs.github.io/aws-lambda-powertools-dotnet/utilities/parameters/](awslabs.github.io/aws-lambda-powertools-dotnet/utilities/parameters/)
+
+GitHub: <https://github.com/awslabs/aws-lambda-powertools-dotnet/>
+
+## Sample Function using AWS Systems Manager Parameter Store
+
+```csharp
+using AWS.Lambda.Powertools.Logging;
+using AWS.Lambda.Powertools.Parameters;
+using AWS.Lambda.Powertools.Parameters.SimpleSystemsManagement;
+
+namespace HelloWorld;
+
+public class Function
+{
+    [Logging(LogEvent = true)]
+    public async Task<APIGatewayProxyResponse> FunctionHandler(APIGatewayProxyRequest apigwProxyEvent,
+        ILambdaContext context)
+    {    
+        // Get SSM Provider instance
+        ISsmProvider ssmProvider = ParametersManager.SsmProvider;
+
+        // Retrieve a single parameter
+        string? value = await ssmProvider
+            .GetAsync("/my/parameter")
+            .ConfigureAwait(false);
+
+        // Retrieve multiple parameters from a path prefix
+        // This returns a Dictionary with the parameter name as key
+        IDictionary<string, string?> values = await ssmProvider
+            .GetMultipleAsync("/my/path/prefix")
+            .ConfigureAwait(false);
+
+        ...
+
+    }
+}
+```