Remove build instructions for Xeon Phi
Remove build instructions for Xeon Phi

walshjon/openmc,walshjon/openmc,shikhar413/openmc,walshjon/openmc,amandalund/openmc,amandalund/openmc,walshjon/openmc,shikhar413/openmc,amandalund/openmc,shikhar413/openmc,amandalund/openmc,shikhar413/openmc