Allowing `_doc` as a type will enable users to make the transition to 7.0
smoother since the index APIs will be `PUT index/_doc/id` and `POST index/_doc`.
This also moves most of the documentation to `_doc` as a type name.
Closes#27750Closes#27751
Remove the arbitrary limit on epoch_millis and epoch_seconds of 13 and 10
characters, respectively. Instead allow any character combination that can
be converted to a Java Long.
Update the docs to reflect this change.
Adrien Grand
Clinton Gormley
Lee Hinman
David Pilato
G. Richard Bellamy