test: Drop fedora-atomic image from README
test: Drop fedora-atomic image from README

Move the example to fedora-testing, as that's also a stable name.

moraleslazaro/cockpit,martinpitt/cockpit,garrett/cockpit,moraleslazaro/cockpit,martinpitt/cockpit,cockpituous/cockpit,cockpituous/cockpit,cockpituous/cockpit,garrett/cockpit,moraleslazaro/cockpit,deryni/cockpit,deryni/cockpit,mvollmer/cockpit,cockpituous/cockpit,cockpituous/cockpit,cockpit-project/cockpit,martinpitt/cockpit,garrett/cockpit,moraleslazaro/cockpit,deryni/cockpit,moraleslazaro/cockpit,cockpit-project/cockpit,deryni/cockpit,deryni/cockpit,moraleslazaro/cockpit,cockpit-project/cockpit,garrett/cockpit,martinpitt/cockpit,cockpit-project/cockpit,mvollmer/cockpit,deryni/cockpit,cockpituous/cockpit,mvollmer/cockpit,martinpitt/cockpit,mvollmer/cockpit,moraleslazaro/cockpit,garrett/cockpit,cockpit-project/cockpit,deryni/cockpit,mvollmer/cockpit