Add WSL section in install-guide.md

[DKAndreasen]

A small addition to the documentation of the container toolkit. After having struggled a bit to get the nvidia runtime to work for docker on windows with WSL, where WSL is used as backend following these docker instructions and this container-toolkit installation guide I figured out that the only change needed was to specify the daemon config file in the windows system. Thus, it would have helped me and will maybe help other to add to the following WSL instructions to the configuring docker subsection

Thanks and kind regards
Signed-off-by: Daniel Andreasen akda@aarhus.dk

[mikemckiernan]

Thanks very much @DKAndreasen! Let me look at this a little more closely over the next day or two. There are some nitpicky formatting items. Unless you say otherwise, I'll push touchup commits to your branch. Please let me know if you prefer otherwise.

[DKAndreasen]

@mikemckiernan you are more than welcome to fix formatting or any other issues you find. If you push them to me, I'll make sure to merge them in and update the pull request. Thanks!