[doc] hide diffusion in application path (#3519)

- [ ] Stable Diffusion
- [ ] Dreambooth
It's easy for users to think that we don't support them yet. Add them after migrating them from example to application
https://github.com/hpcaitech/ColossalAI/tree/main/examples/images

applications/README.md

@@ -5,10 +5,8 @@ This directory contains the applications that are powered by Colossal-AI.
 The list of applications include:
 
 - [X] [Chatbot](./Chat/README.md)
-- [ ] Stable Diffusion
-- [ ] Dreambooth
 - [X] [FastFold](https://github.com/hpcaitech/FastFold): Optimizing AlphaFold (Biomedicine) Training and Inference on GPU Clusters
 
 > Please note that the `Chatbot` application is migrated from the original `ChatGPT` folder.
 
-You can find more example code for the base model and functions in the [Examples](https://github.com/hpcaitech/ColossalAI/tree/main/examples) directory.
\ No newline at end of file
+You can find more example code for base models and functions in the [Examples](https://github.com/hpcaitech/ColossalAI/tree/main/examples) directory.