io/fs: no examples for how to use it with the operating system

[FiloSottile]

I needed to walk a directory, so I pulled up the io/fs.WalkDir docs, but there was nothing telling me how to get an FS instance for the operating system's filesystem. The only mention of os.DirFS is in fs.Sub, and I only found it because I had a hunch to search os..

[adammitha]

Hi Filippo! I ran into this issue as well - are you still looking for help developing an example for this use case?

[gopherbot]

Change https://golang.org/cl/319989 mentions this issue: io/fs: added an example for io/fs.WalkDir