State visualizer sample readme is outdated

Describe the bug The readme at https://github.com/microsoft/Quantum/tree/main/samples/runtime/state-visualizer looks out of sync with the code. The instructions suggest to edit Program.qs file, looking for QsMain operation, and neither exist. (Instead, the visualizer picks up whichever Q# operation is called from Program.cs, and in the sample this operation is from a different sample, rather than contained in this one.)

It would also be convenient to clarify that commands npm install and npm run release should be executed from the sample directory (I started by running them from elsewhere and got a bunch of confusing errors), and to specify whether they are part of one-time install or per-project setup.