Clarify KCCSD energy expression and fix example in main()
Clarify KCCSD energy expression and fix example in main()

gkc1000/pyscf,sunqm/pyscf,gkc1000/pyscf,sunqm/pyscf,sunqm/pyscf,gkc1000/pyscf,gkc1000/pyscf,sunqm/pyscf,gkc1000/pyscf