Update README.md

Update demo and usage links

README.md

@@ -29,13 +29,11 @@ Hindi (hi), **Vietnamese (vi)**.
   
 ### Demo
 
-Update later
+Please checkout [this repo](https://github.com/thinhlpg/vixtts-demo)
 
 ### Usage
 
-```python
-# Update later
-```
+For a quick usage, please checkout [this notebook](https://colab.research.google.com/drive/1q9vA7mDyvK_u0ijDDNuycDoUUbryM3p3?usp=sharing)
 
 ### License