I'd suggest a simple rewording the first sentence in the section from:
Ubuntu is built on the foundation of Linux, which is a member of the Unix family.
to:
Linux is a member of the UNIX(R) family of operating systems, and is the foundation on which Ubuntu is built.
I'd suggest a simple rewording the first sentence in the section from:
Ubuntu is built on the foundation of Linux, which is a member of the Unix family.
to:
Linux is a member of the UNIX(R) family of operating systems, and is the foundation on which Ubuntu is built.