Add missing dependency to tracing docs (#6421)

## Why are these changes needed?

Add missing dependency to tracing docs

<!-- Please give a short summary of the change and the problem this
solves. -->

## Related issue number

<!-- For example: "Closes #1234" -->

Closes #6419

## Checks

- [ ] I've included any doc changes needed for
<https://microsoft.github.io/autogen/>. See
<https://github.com/microsoft/autogen/blob/main/CONTRIBUTING.md> to
build and test documentation locally.
- [ ] I've added tests (if relevant) corresponding to the changes
introduced in this PR.
- [ ] I've made sure all auto checks have passed.

python/packages/autogen-core/docs/src/user-guide/agentchat-user-guide/tracing.ipynb

@@ -15,7 +15,7 @@
                 "To begin, you need to install the OpenTelemetry Python package. You can do this using pip:\n",
                 "\n",
                 "```bash\n",
-                "pip install opentelemetry-sdk\n",
+                "pip install opentelemetry-sdk opentelemetry-exporter-otlp-proto-grpc\n",
                 "```\n",
                 "\n",
                 "Once you have the SDK installed, the simplest way to set up tracing in AutoGen is to:\n",
@@ -374,7 +374,8 @@
             "metadata": {},
             "source": [
                 "\n",
-                "In the code above, we create a new span for each message sent by the agent. We set attributes on the span to include the agent's name and the message content. This allows us to trace the flow of messages through our application and understand how they are processed."
+                "In the code above, we create a new span for each message sent by the agent. We set attributes on the span to include the agent's name and the message content. This allows us to trace the flow of messages through our application and understand how they are processed. \n",
+                " "
             ]
         }
     ],