[DOCS] Update Dataset.md after PR 36

[roysti10]

Is your feature request related to a problem? Please describe.
After #36 the entire dataset has been restructured, those changes need to reflected in Dataset.md
The file structure can be found in the descriptions of #36

Describe the solution you'd like
Since zip, zip2,Bowl and wk folders no longer exist, they need to removed , the scoring table remains same,
Two folders have been added namely ODI and T20
Each having 4 folders containing the joint files of zip,zip2,Bowl and wk
this needs to reflected