OGM-680 Minor fix
OGM-683 Improve mongodb documentation around configuration
OGM-685 Rename to AssociationDocumentStorageType
OGM-685 Update documentation with new AssociationDocumentStorageType name
OGM-683 Improve MongoDB documentation (beginning of storage principles)
OGM-681 [MongoDB] Add embedded id examples for manytoone and manytomany