update wsl2 ubuntu 18 to 20.04 code example

Example: update to wsl2

#enable wsl 
dism.exe /online /enable-feature /featurename:Microsoft-Windows-Subsystem-Linux /all /norestart
#make sure windows version is >=2004
dism.exe /online /enable-feature /featurename:VirtualMachinePlatform /all /norestart
#restart
wsl --set-default-version 2
#if kernal error https://docs.microsoft.com/en-us/windows/wsl/wsl2-kernel