Update link in README

Author: soimkim

README.md

@@ -37,7 +37,7 @@ For windows, you need to install [Microsoft Visual C++ Build Tools][ms_build].
 
 ## 🎉 How to install
 
-It can be installed using pip3. It is recommended to install it in the [python 3.6 + virtualenv](docs/Guide_virtualenv.md) environment.
+It can be installed using pip3. It is recommended to install it in the [python 3.6 + virtualenv](https://github.com/fosslight/fosslight_source/blob/main/docs/Guide_virtualenv.md) environment.
 
 ```
 $ pip3 install fosslight_source