Add memory frequency, type, and slot information

[amone-bit]

Add memory frequency, type, and slot information.
Whether there are memory sticks on the different slots, what is the frequency of the memory sticks on them, what is the size of the memory, I would like to have more detailed information instead of giving me a generalized information like total memory, used memory and so on

[GuillaumeGomez]

That'd be nice to have indeed. Not a priority though so I won't work on it before a long time. Don't hesitate to send a PR to implement it though!