Add option to show Disk IO

[ChillarAnand]

Most of the activity monitoring tools display disk io. Sometimes one of the programs might be doing a lot of disk io which might slow the system. Can we add an option to show disk io as well?

[D0miH]

Hey @ChillarAnand,

indeed most of the other tools are displaying disk info. Seems like a good idea to me. If you want to implement it, feel free to open a PR:)