Load CC amplitude from FCHK & Add documentation

[FarnazH]

A few useful IOp that will ensure that interesting data is in fchk files. IOp(9/11=1) [store CC amplitudes]. Probalby also MP amplitudes and CISD coefficients, but ambiguous (= bad) documentation.

Unfortunately I could not find an option to print out MOs and DMs all along a trajectory/IRC.

Originally posted by @PaulWAyers in https://github.com/theochem/iodata/issues/139#issuecomment-662206832