Add comments for metamodel module => DONE

src/app/metamodel/action/attribute.action.ts

src/app/metamodel/action/criteria.action.ts

src/app/metamodel/action/dataset.action.ts

src/app/metamodel/action/instance.action.ts

src/app/metamodel/action/output.action.ts

src/app/metamodel/effects/attribute.effects.ts

src/app/metamodel/effects/criteria.effects.ts

src/app/metamodel/effects/dataset.effects.ts

src/app/metamodel/effects/instance.effects.ts

src/app/metamodel/effects/output.effects.ts

src/app/metamodel/metamodel.module.ts

src/app/metamodel/model/attribute.model.ts

src/app/metamodel/model/attributes-by-dataset.model.ts

src/app/metamodel/model/category.model.ts

src/app/metamodel/model/dataset.model.ts

src/app/metamodel/model/family.model.ts

src/app/metamodel/model/instance.model.ts

src/app/metamodel/model/option.model.ts

src/app/metamodel/model/project.model.ts

src/app/metamodel/model/renderer-config.model.ts