Docs: re-run of the test on the existing namespace does not create pods

[vmware-tanzu]

Docs: re-run of the test on the existing namespace does not create pods

[kensimon]

This is the case even if sonobuoy runs sucessfully... the pod stays around so that you can kubectl cp the output tarball locally. In order to re-run sonobuoy you need to delete the pod (or the whole namespace) and recreate it.

Re-titling this, I think our docs need to be fixed to make this more clear.

[kensimon]

@abiogenesis-now who may be interested in updating the README here

[kensimon]

Closing this since we have more clarity in the docs now