Move Use OpenAI Compatible LLM Server section to existing advanced page

Add footnote on supported chat models to the self-hosting section

documentation/docs/miscellaneous/advanced.md

@@ -4,13 +4,13 @@ sidebar_position: 3
 
 # Advanced Usage
 
-### Search across Different Languages (Self-Hosting)
+## Search across Different Languages (Self-Hosting)
 To search for notes in multiple, different languages, you can use a [multi-lingual model](https://www.sbert.net/docs/pretrained_models.html#multi-lingual-models).<br />
 For example, the [paraphrase-multilingual-MiniLM-L12-v2](https://huggingface.co/sentence-transformers/paraphrase-multilingual-MiniLM-L12-v2) supports [50+ languages](https://www.sbert.net/docs/pretrained_models.html#:~:text=we%20used%20the%20following%2050%2B%20languages), has good search quality and speed. To use it:
 1. Manually update the search config in server's admin settings page. Go to [the search config](http://localhost:42110/server/admin/database/searchmodelconfig/). Either create a new one, if none exists, or update the existing one. Set the bi_encoder to `sentence-transformers/multi-qa-MiniLM-L6-cos-v1` and the cross_encoder to `cross-encoder/ms-marco-MiniLM-L-6-v2`.
 2. Regenerate your content index from all the relevant clients. This step is very important, as you'll need to re-encode all your content with the new model.
 
-### Query Filters
+## Query Filters
 
 Use structured query syntax to filter entries from your knowledge based used by search results or chat responses.
 
@@ -30,3 +30,25 @@ Use structured query syntax to filter entries from your knowledge based used by
     - containing dates from the year *1984*
     - excluding words *"big"* and *"brother"*
     - that best match the natural language query *"what is the meaning of life?"*
+
+## Use OpenAI compatible LLM API Server (Self Hosting)
+Use this if you want to use non-standard, open or commercial, local or hosted LLM models for Khoj chat
+1. Setup your desired chat LLM by installing an OpenAI compatible LLM API Server like [LiteLLM](https://docs.litellm.ai/docs/proxy/quick_start), [llama-cpp-python](https://github.com/abetlen/llama-cpp-python?tab=readme-ov-file#openai-compatible-web-server)
+2. Set environment variable `OPENAI_API_BASE="<url-of-your-llm-server>"` before starting Khoj
+3. Add ChatModelOptions with `model-type` `OpenAI`, and `chat-model` to anything (e.g `gpt-4`) during [Config](/get-started/setup#3-configure)
+   - *(Optional)* Set the `tokenizer` and `max-prompt-size` relevant to the actual chat model you're using
+
+#### Sample Setup using LiteLLM and Mistral API
+
+```shell
+# Install LiteLLM
+pip install litellm[proxy]
+
+# Start LiteLLM and use Mistral tiny via Mistral API
+export MISTRAL_API_KEY=<MISTRAL_API_KEY>
+litellm --model mistral/mistral-tiny --drop_params
+
+# Set OpenAI API Base to LiteLLM server URL and start Khoj
+export OPENAI_API_BASE='http://localhost:8000'
+khoj --anonymous-mode
+```