Assuming you have the WSL extension for vs code installed

Open WSL, use the cd command to navigate to the folder that contains the readme file, the c drive is located under /mnt/c if im not mistaken, then you can run code . to open the current directory in vs code, or code readme.md to open the readme file

Theoretically if everything works at the bottom of the vs code page you should see an indicator saying it’s running in WSL