README: Document pkg-config issue with source install of OSSP uuid
README: Document pkg-config issue with source install of OSSP uuid

- Document the fact that configure checks for the OSSP uuid pkg-config
name provided by the Fedora and Debian binary packages, not the one
provided by a source install

cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr