Mention the manual page and "onedriver --help" in the README

[foopsss]

Extended the paragraph after "Microsoft OneDrive works on Linux" to mention the availability of the man page and "onedriver --help", so users know a way to get a list with all the available arguments to run onedriver.

I thought this would be useful after coming across issue #381. I didn't want to add an explanation with all the parameters because that would just be repetitive when the manpage is more than enough, so this is probably alright.

[foopsss]

On a completely unrelated note, I think the naming conventions thing mentioned by abraunegg in #387 is worth adding to the README as well, although it could go in another PR.