(docs) using litellm proxy + Langfuse

docs/my-website/docs/simple_proxy.md

@@ -710,6 +710,34 @@ https://api.openai.com/v1/chat/completions \
 ```
 
 ## Logging Proxy Input/Output - Langfuse
+We will use the `--config` with the proxy for logging input/output to Langfuse
+- We will use the `litellm.success_callback = ["langfuse"]` this will log all successfull LLM calls to langfuse
+
+**Step 1**: Create a `config.yaml` file
+```yaml
+model_list:
+ - model_name: gpt-3.5-turbo
+    litellm_params:
+      model: gpt-3.5-turbo
+  - model_name: gpt-4-team1
+    litellm_params:
+      model: azure/chatgpt-v-2
+      api_base: https://openai-gpt-4-test-v-1.openai.azure.com/
+      api_version: "2023-05-15"
+litellm_settings:
+  success_callback: ["langfuse"]
+```
+
+**Step 2**: Start the proxy, make a test request
+```shell
+litellm --model gpt-3.5-turbo --debug
+```
+
+Test Request
+```
+litellm --test
+```
+
 
 ## Proxy CLI Arguments