Troubleshooting: document third-party AV hardware virtualization as a cause of Wsl/...HCS/ERROR_NOT_SUPPORTED

[bmdockersupport]

A user reported Docker Desktop failing to start on Windows with:

running wslexec: An error occurred while running the command.
Wsl/Service/RegisterDistro/CreateVm/HCS/ERROR_NOT_SUPPORTED: c:\windows\system32\wsl.exe --import-in-place docker-desktop <home>\appdata\local\docker\wsl\main\ext4.vhdx:
exit status 0xffffffff (stderr: , stdout: The request is not supported.
Error code: Wsl/Service/RegisterDistro/CreateVm/HCS/ERROR_NOT_SUPPORTED, wslErrorCode: Wsl/Service/RegisterDistro/CreateVm/HCS/ERROR_NOT_SUPPORTED)

Disabling Avast's "hardware-assisted virtualization" setting resolved it.

Two gaps in content/manuals/desktop/troubleshoot-and-support/troubleshoot/topics.md:

1. "Docker Desktop fails to start when anti-virus software is installed" lists only uninstalling the anti-virus or adding Docker to its exclusions. Neither releases the hardware virtualization extensions, so neither addresses this case.
2. "Docker Desktop fails due to Virtualization not working" names Wsl/Service/RegisterDistro/CreateVm/HCS/HCS_E_HYPERV_NOT_INSTALLED but not the ERROR_NOT_SUPPORTED variant, which is the string a user in this situation will actually search for.

Suggested change:

• Add ERROR_NOT_SUPPORTED alongside the existing HCS error code in the virtualization section.
• Add a bullet to the anti-virus section covering AV products that enable their own hardware-assisted virtualization or hardened/sandbox mode, with "disable that feature" as the thing to try.

Reported via Docker Support case 00233437.

[zaricu22]

Bug is presented on newest 4.89.0, but also on older versions of Docker Desktop (Personal use).
On Windows machine Avast always runs first and get this exclusive privilege for Hyper-V,
blocking other software from access this feature and running WSL.
To disable this AV feature, follow:
Menu -> Settings -> Troubleshooting -> Uncheck: Enable hardware-assisted virtualization.