Replace "file(s)" with "file" or "files"

[hugovk]

Instead of:

With the provided path, there will be 1 file(s) uploaded

Show either:

With the provided path, there will be 1 file uploaded

Or:

With the provided path, there will be 2 files uploaded

[konradpabjan]

Thanks for the PR!

Making changes to any files under src/* also requires dist/index.js to be rebuilt using npm run release. I'll take care of that though since I'm working on a new release in another PR.