Wrong directory separator on Windows

[nirebu]

I was trying to use your plugin to autobuild the navbar and sidebar, but I found an issue while using the structure nav.foldername to build the navbar.

The plugin would build the $themeConfig.nav[].link as \nav.foldername\, thus breaking the navigation and sidebar loading.

I nailed down the cause to being on Windows, because the same config, run through a Linux VM works no problem, generating the parameters right as /nav.foldername/ both in the nav object and sidebar groups keys.

Is there a way to hardcode the correct browser separator to be / ?

Thank you very much

[ozum]

Thanks for the PR.