Document Reference Data: the big plan

[mickaelandrieu]

• [X] How to create a Reference Data (https://docs.akeneo.com/1.6/cookbook/catalog_structure/creating_a_reference_data.html)
• [X] Document the Menu management (needed to create a CRUD)
• [x] Document the CustomEntityBundle: forms, actions, grids (https://github.com/akeneo/pim-docs/pull/495)
• [x] How to create a CRUD for a Reference Data (using CustomEntityBundle) (https://github.com/akeneo/pim-docs/pull/494) ? (cookbook/crud_reference_data)
• [x] How to link a reference data to a product type ? (need to be updated) (https://docs.akeneo.com/1.2/cookbook/custom_entity/creating_an_attribute_type.html)
• [ ] Document the Datagrid management (/reference/datagrid , needed to display a CRUD)
• [x] What is a Reference Data (/reference/reference_data)