Tutorial documentation/files need minor update?

[ChristopherDrum]

Describe the bug

Documentation in basic-tutorial.md references a file at the path
grpc-swift/Sources/Examples/RouteGuide/Client/main.swift
but this file does not exist (see screenshot).

Presumably it is meant to point to RouteGuideClient.swift
The existence of Empty.swift also seems suspicious to me.

Expected behaviour

Just expect documentation to keep up to date with the code changes (and vice versa).

[glbrntt]

Thanks @ChristopherDrum, do you want to open a PR to fix this?

[ChristopherDrum]

@glbrntt Sure, I can do that. I'll see if anything else obvious comes up during my tutorial walkthrough today and make a PR when I finish.