fix: update llm_streaming_stream_method.ts doc (#2929)

* fix: update llm_streaming_stream_method.ts doc

Removes reference to `handleLLMNewToken` since `handleLLMNewToken` does not exist within this example

* Adds `streaming: true` to docs

Adds missing property in the expected configuration for streaming

* Update llm_streaming_stream_method.ts

Remove unneeded comments and unnecessary code
- `.stream()` works without the need to add `streaming: true` as part of the LLM constructor

examples/src/models/llm/llm_streaming_stream_method.ts

@@ -1,7 +1,5 @@
 import { OpenAI } from "langchain/llms/openai";
 
-// To enable streaming, we pass in `streaming: true` to the LLM constructor.
-// Additionally, we pass in a handler for the `handleLLMNewToken` event.
 const model = new OpenAI({
   maxTokens: 25,
 });