Add an example for uploadManyFiles method

[xephtar]

I am using older version of nodejs-storage. I had an issue about uploading many files into custom path. There is no option to upload custom path with using uploadManyFiles method. But I found an issue that solves this. But there is no example implementation to handle the case.

Can you add an example to upload many files into custom path?

[xephtar]

@ddelgrosso1 I created the issue 🙏

[ddelgrosso1]

Thanks @xephtar!

[individual8]

I'd also be interested in an example. I'm kinda already on it, but have difficulties with directory separators (/ vs. \) from Windows file system. I set the the directory in Node with forward slashes, customDestinationBuilder however seem to serve the path with double-backslashes. 🤷