Update README.md

Fixed typo in example code, resolve #1000

README.md

@@ -144,7 +144,7 @@ ChatSession session = new(executor, chatHistory);
 InferenceParams inferenceParams = new InferenceParams()
 {
     MaxTokens = 256, // No more than 256 tokens should appear in answer. Remove it if antiprompt is enough for control.
-    AntiPrompts = new List<string> { "User:" } // Stop generation once antiprompts appear.
+    AntiPrompts = new List<string> { "User:" }, // Stop generation once antiprompts appear.
 
     SamplingPipeline = new DefaultSamplingPipeline(),
 };