[#3] Update Regions Documentation and add a figure of regions table (#16

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* [#3] Update Regions Documentation and add a figure of regions table

* [#3] Update Region Documentation based on review

* [#3] Update Region Documentation based on 2nd review

* [#3] add region code must be unique and remove the last line that does not need comma

* [#3] Update region-layer

* [#3] Rename regions.png to region-layer.png

* [#3] Remove company_code and kunci from regions table