update url reference (#5286)

Author: lucas-zimerman

src/includes/performance/traces-sampler-as-sampler/dotnet.aspnetcore.mdx

@@ -0,0 +1,38 @@
+```csharp
+using Sentry;
+
+// Add this to the SDK initialization callback
+// To set a uniform sample rate
+options.TracesSampleRate = 1.0;
+
+// OR: Determine traces sample rate based on the sampling context
+options.TracesSampler = context =>
+{
+    // If this is the continuation of a trace, just use that decision (rate controlled by the caller)
+    if (context.TransactionContext.IsParentSampled is not null)
+    {
+        return context.TransactionContext.IsParentSampled.Value
+            ? 1.0
+            : 0.0;
+    }
+
+    // Otherwise, sample based on URL (exposed through custom sampling context)
+    return context.CustomSamplingContext.GetValueOrDefault("url") switch
+    {
+        // These are important - take a big sample
+        "/payment" => 0.5,
+
+        // Search is less important and happen much more frequently - only take 1%
+        "/search" => 0.01,
+
+        // The health check endpoint is just noise - drop all transactions
+        "/health" => 0.0,
+
+        // Default sample rate
+        _ => 0.1
+
+        // Or return null to fallback to options.TracesSampleRate (1.0 in this case)
+        // _ => null
+    };
+};
+```

src/includes/performance/traces-sampler-as-sampler/dotnet.mdx

@@ -17,7 +17,7 @@ options.TracesSampler = context =>
     }
 
     // Otherwise, sample based on URL (exposed through custom sampling context)
-    return context.CustomSamplingContext.GetValueOrDefault("url") switch
+    return context.CustomSamplingContext.GetValueOrDefault("__HttpPath") switch
     {
         // These are important - take a big sample
         "/payment" => 0.5,