Add google colab version and guide for it

Author: daswer123

README.md

@@ -1,6 +1,7 @@
 # A simple FastAPI Server to run XTTSv2
 
 There's a [google collab version](https://colab.research.google.com/drive/1b-X3q5miwYLVMuiH_T73odMO8cbtICEY?usp=sharing) you can use it if your computer is weak.
+You can check out the [guide](https://rentry.org/xtts-api-server-colab-guide)
 
 This project is inspired by [silero-api-server](https://github.com/ouoertheo/silero-api-server) and utilizes [XTTSv2](https://github.com/coqui-ai/TTS).