This commit is a correction of a doc bug in the docs for the ingest
date-index-name processor. The correct pattern is
yyyy-MM-dd'T'HH:mm:ss.SSSXX. This is due to the transition from Joda
time to Java time where Z does not mean the same thing between the two.
As mapping types are being removed throughout Elasticsearch, the use of
`_type` in pipeline simulation requests is deprecated. Additionally, the
default `_type` used if one is not supplied has been changed to `_doc` for
consistency with the rest of Elasticsearch.
This commit breaks the single ingest docs file into multiple files,
factoring out the processor docs into a documentation file per
processor. This will help make this content easier to maintain.