Update README.md with usage example

README.md

@@ -2,3 +2,18 @@
 
 Provides the `HttpContext.GetRequestCacheControl()` extension method for accessing 
 the HTTP/1.1 `Cache-Control` and HTTP/1.0 `Pragma` header directives.
+
+## Usage example
+
+Register the Cache-Control middleware on your `IApplicationBuilder`:
+
+```csharp
+app.UseCacheControlMiddleware();
+```
+
+From within your action, use the `GetRequestCacheControl` extension
+method on the HTTP context to get the Cache-Control header information:
+
+```csharp
+ICacheControl cacheControl = HttpContext.GetRequestCacheControl();
+```

src/Nyris.Extensions.AspNetCore.CacheControl.Abstractions/ICacheControl.cs

@@ -10,8 +10,8 @@ public interface ICacheControl
     ///     <c>Pragma</c> request header was present.
     /// </summary>
     /// <remarks>
-    /// If this property evaluates to <see langword="false"/>, all properties of this
-    /// instance will have their default value.
+    ///     If this property evaluates to <see langword="false"/>, all properties of this
+    ///     instance will have their default value.
     /// </remarks>
     bool HeaderUsed { get; }