incorrect command in "build on windows" wiki

[NotADinosaur]

In the prepare interface section, the command to set the JELLYFIN_WEB_DIR variable assumes the jellyfin-web directory is always located in C:/jellyfin, which causes an error if that is not true. The command is correct in the linux build page. I created a fork to try to fix this myself but I decided to make this an issue instead since my writing style may not be consistent with the rest of the wiki. An example of the error that happens if you set it to the wrong directory:

[dmitrylyzo]

There is a note:

The JELLYFIN_WEB_DIR environment variable can be used to override the location of jellyfin-web.

At most, it could be JELLYFIN_WEB_DIR=..\jellyfin-web\dist, but this still assumes that the repos are located in the same directory.