OGM-683 Minor typo
OGM-690 Make each datastore a top level chapter and improve generic datastore provider chapter
OGM-673 Mention embedded objects and @Column in MongoDB documentation
OGM-673 Add @AttributeOverride example and one messing with nested structure
OGM-683 Remove reference of ex-experimental features
OGM-683 Move Opt locking section out of the query section (MongoDB)
OGM-683 Various mongodb doc improvements
OGM-683 Improve Neo4J documentation
Minor doc improvement
OGM-683 Add Davide as author
OGM-603 Put mapping and query chapters before datastores

This opens up the ability to add an "API" section between mapping and query
OGM-360 OGM-687 Rework query chapter entirely
OGM-360 Describe various ways to create a native query
OGM-683 Minor fixes in documentation

  * Replace "Builtin" with "Built-in" for consistency
  * Replace "in-entity" with "in entity" for consistency
  * Typos and minor fixes