Support Ollama (#261)

### What problem does this PR solve?

Issue link:#221

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

docs/ollama.md

@@ -0,0 +1,40 @@
+# Ollama
+
+<div align="center" style="margin-top:20px;margin-bottom:20px;">
+<img src="https://github.com/infiniflow/ragflow/assets/12318111/2019e7ee-1e8a-412e-9349-11bbf702e549" width="130"/>
+</div>
+
+One-click deployment of local LLMs, that is [Ollama](https://github.com/ollama/ollama).
+
+## Install
+
+- [Ollama on Linux](https://github.com/ollama/ollama/blob/main/docs/linux.md)
+- [Ollama Windows Preview](https://github.com/ollama/ollama/blob/main/docs/windows.md)
+- [Docker](https://hub.docker.com/r/ollama/ollama)
+
+## Launch Ollama
+
+Decide which LLM you want to deploy ([here's a list for supported LLM](https://ollama.com/library)), say, **mistral**:
+```bash
+$ ollama run mistral
+```
+Or,
+```bash
+$ docker exec -it ollama ollama run mistral
+```
+
+## Use Ollama in RAGFlow
+
+- Go to 'Settings > Model Providers > Models to be added > Ollama'.
+    
+<div align="center" style="margin-top:20px;margin-bottom:20px;">
+<img src="https://github.com/infiniflow/ragflow/assets/12318111/2019e7ee-1e8a-412e-9349-11bbf702e549" width="130"/>
+</div>
+
+> Base URL: Enter the base URL where the Ollama service is accessible, like, http://<your-ollama-endpoint-domain>:11434
+
+- Use Ollama Models.
+
+<div align="center" style="margin-top:20px;margin-bottom:20px;">
+<img src="https://github.com/infiniflow/ragflow/assets/12318111/2019e7ee-1e8a-412e-9349-11bbf702e549" width="130"/>
+</div>