Finish defining the mapping of the LinGBM GraphQL schema to the RDB schema of the dataset generator

[hartig]

The mapping is defined on the following wiki page, but it is not complete yet.
https://github.com/LiUGraphQL/LinGBM/wiki/Mapping-of-GraphQL-Schema-to-Relational-Schema-TODO

/cc @chengsijin0817

[VladimirAlexiev]

Also, merge:

• https://github.com/LiUGraphQL/LinGBM/wiki/Mapping-of-GraphQL-Schema-to-Relational-Schema(TODO)
• https://github.com/LiUGraphQL/LinGBM/wiki/Mapping-of-GraphQL-Schema-to-Relational-Schema-TODO

[chengsijin0817]

Hi @VladimirAlexiev, thanks a lot for pointing it out.
The "Mapping-of-GraphQL-Schema-to-Relational-Schema(TODO)" is the old version.
I have removed it now.