Add comprehensive documentation and examples for HTTP QUERY method

- Create detailed usage examples for HttpMethods.Query
- Show MVC controller examples with HttpQueryAttribute
- Demonstrate minimal API usage with MapQuery
- Include HTTP client examples
- Document benefits and use cases of QUERY method
- All functionality fully implemented and tested

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

Author: Copilot

HTTP_QUERY_USAGE_EXAMPLES.md

@@ -0,0 +1,117 @@
+# HTTP QUERY Method Support in ASP.NET Core
+
+This document provides examples of how to use the new HTTP QUERY method support added to ASP.NET Core.
+
+## HttpMethods Class
+
+The `HttpMethods` class now includes support for the QUERY method:
+
+```csharp
+using Microsoft.AspNetCore.Http;
+
+// New QUERY method constant
+string queryMethod = HttpMethods.Query; // "QUERY"
+
+// New IsQuery method
+bool isQuery = HttpMethods.IsQuery("QUERY"); // true
+bool isQueryLowercase = HttpMethods.IsQuery("query"); // true
+
+// GetCanonicalizedValue now supports QUERY
+string canonicalized = HttpMethods.GetCanonicalizedValue("query"); // Returns HttpMethods.Query
+```
+
+## MVC Controller Support
+
+Use the new `HttpQueryAttribute` in MVC controllers:
+
+```csharp
+using Microsoft.AspNetCore.Mvc;
+
+[ApiController]
+[Route("api/[controller]")]
+public class DataController : ControllerBase
+{
+    [HttpQuery]
+    public IActionResult Search([FromQuery] string q, [FromQuery] int limit = 10)
+    {
+        // Handle QUERY request with query parameters in the body
+        return Ok(new { query = q, limit = limit });
+    }
+    
+    [HttpQuery("search/{category}")]
+    public IActionResult SearchByCategory(string category, [FromQuery] string q)
+    {
+        // Handle QUERY request with both route and query parameters
+        return Ok(new { category = category, query = q });
+    }
+}
+```
+
+## Minimal API Support
+
+Use the new `MapQuery` extension methods with minimal APIs:
+
+```csharp
+using Microsoft.AspNetCore.Http;
+
+var builder = WebApplication.CreateBuilder(args);
+var app = builder.Build();
+
+// MapQuery with RequestDelegate
+app.MapQuery("/search", async (HttpContext context) =>
+{
+    var query = context.Request.Query["q"].ToString();
+    return Results.Ok(new { query = query });
+});
+
+// MapQuery with typed delegate
+app.MapQuery("/search/{category}", (string category, string q) =>
+{
+    return Results.Ok(new { category = category, query = q });
+});
+
+// MapQuery with async delegate
+app.MapQuery("/async-search", async (string q, ILogger<Program> logger) =>
+{
+    logger.LogInformation("Processing query: {Query}", q);
+    await Task.Delay(100); // Simulate async work
+    return Results.Ok(new { query = q, timestamp = DateTime.UtcNow });
+});
+
+app.Run();
+```
+
+## Usage with HTTP Clients
+
+Example of making QUERY requests:
+
+```csharp
+using System.Net.Http;
+
+var client = new HttpClient();
+
+// Simple QUERY request
+var request = new HttpRequestMessage(new HttpMethod("QUERY"), "https://api.example.com/search?q=test");
+var response = await client.SendAsync(request);
+
+// QUERY request with content body (if supported by the API)
+var queryRequest = new HttpRequestMessage(new HttpMethod("QUERY"), "https://api.example.com/advanced-search")
+{
+    Content = JsonContent.Create(new { 
+        query = "search terms", 
+        filters = new { category = "books", minPrice = 10 } 
+    })
+};
+var queryResponse = await client.SendAsync(queryRequest);
+```
+
+## Benefits of HTTP QUERY Method
+
+The HTTP QUERY method is designed for safe queries that may include request bodies:
+
+- **Safe**: Like GET, QUERY requests should not modify server state
+- **Cacheable**: QUERY responses can be cached like GET responses  
+- **Request Body**: Unlike GET, QUERY allows request bodies for complex query parameters
+- **Semantic Clarity**: Clearly indicates query operations vs. data retrieval (GET)
+
+For more information, see the HTTP QUERY method specification: https://datatracker.ietf.org/doc/draft-ietf-httpbis-safe-method-w-body/