Update comments in app.windows.bundle with correct cli command

[marlenecota]

The file currently mentions "--platform windows" which is not valid. It also has inconsistent naming (app.windows.js vs index.windows.bundle)

• Update platform listed in comment
• Fix inconsistent naming
• Add bundle script to package.json

[kmelmon]

@marlenecota can you clarify what's needed here, and if a CLI update is needed, enlist Margaryta's help in getting the CLI updated?

[marlenecota]

The only CLI changes happening are documentation.

https://github.com/microsoft/react-native-windows/blob/master/vnext/local-cli/generator-windows/templates/app.windows.bundle

That file has instructions on how to generate a bundle, but they weren't updated after the platform and some files were renamed.

[kmelmon]

gotcha thanks - I'll leave this assigned to you then.