  We use inelastic neutron scattering to study energy and wave vector
dependence of the superconductivity-induced resonance in hole-doped
Ba$_{0.67}$K$_{0.33}$(Fe$_{1-x}$Co$_{x}$)$_{2}$As$_{2}$ ($x=0,0.08$ with
$T_c\approx 37, 28$ K, respectively). In previous work on electron-doped
Ba(Fe$_{0.963}$Ni$_{0.037}$)$_2$As$_2$ ($T_N=26$ K and $T_c=17$ K), the
resonance is found to peak sharply at the antiferromagnetic (AF) ordering wave
vector ${\bf Q}_{\rm AF}$ along the longitudinal direction, but disperses
upwards away from ${\bf Q}_{\rm AF}$ along the transverse direction. For hole
doped $x=0, 0.08$ without AF order, we find that the resonance displays
ring-like upward dispersion away from ${\bf Q}_{\rm AF}$ along both the
longitudinal and transverse directions. By comparing these results with
calculations using the random phase approximation, we conclude that the
dispersive resonance is a direct signature of isotropic superconducting gaps
arising from nested hole-electron Fermi surfaces.
