Add a new document for designing data table.

[BeerShigachi]

Please add this image to this repository https://discord.com/channels/1027042340004691968/1110859143084003398/1161218770333876254

• [x] create docs/data_management
• [x] save the image to the directory. the image should be named table_design_policy or something clear.

[ShunMiya]

@BeerShigachi I created a working branch and linked it to the issue.