Should document that the tar extraction will strip 1 leading component of filenames

[Gnarus-G]

I apologize if this is actually documented somewhere outside of the code. I couldn't find it.

Currently, if your tarball looks like

file
dir/file

since strip is set to 1, you lose file, and most annoyingly if your whole tarball is just single file name components, you lose everything in the extraction - I just wrestled with this case myself before I learned all this about tar and the strip option.

I propose documenting this stripping as core assumption of binary-install, so people know how to pack their balls.