Added virtualenv specifics for Windows (#20540)

Added the specific command to be executed on a Microsoft Windows-based system.

guide/english/python/virtual-environments/index.md

@@ -51,10 +51,20 @@ lsvirtualenv
 
 ### Activate an Environment
 
+Note : On Windows, activating a virtual environment requires the user to have the permission to run scripts.
+
 Before you can start using the environment you need to activate it:
+
+For Mac OS or Linux systems : 
+
 ```
 source my-env/bin/activate
 ```
+And for Windows : 
+
+```
+.\my-env\Scripts\activate.bat
+```
 
 This ensures that only packages under `my-env/` are used.