Ignore node_modules in standalone mode

[qpwo]

Thank you for making this!

I have a project with some subprojects using VGI. My src is not in a src subdir so I have to find and pass all the right filenames, otherwise VGIS takes forever. If VGIS ignored node_modules, then I think just running vgis . in a huge layered project would be reasonably fast.

I think it's as simple as passing an option to globby at https://github.com/fjc0k/vscode-generate-index/blob/master/src/generateIndex.ts#L76

I tried ignore: ['**/node_modules/**'] but that wasn't quite right. I don't think it would be complicated though.