Restructures the 'Update an enrich policy' section to:
* Migrate the content to the section. It was previously stored in the
Put Enrich Policy API docs.
* Remove the warning tag admonition from the section content.
* Replace a reused section earlier in the "Set up an enrich processor"
page with a link.
No substantive changes were made to the content.
Prior to this change the `target_field` would always be a json array
field in the document being ingested. This to take into account that
multiple enrich documents could be inserted into the `target_field`.
However the default `max_matches` is `1`. Meaning that by default
only a single enrich document would be added to `target_field` json
array field.
This commit changes this; if `max_matches` is set to `1` then the single
document would be added as a json object to the `target_field` and
if it is configured to a higher value then the enrich documents will be
added as a json array (even if a single enrich document happens to be
enriched).
* Add enrich policy common parameter
* Add enrich APIs to REST APIs index
* Add put enrich policy API docs
* Add get enrich policy API docs
* Add delete enrich policy API docs
* Add execute enrich policy API docs
Lisa Cawley
James Rodewig
Martijn van Groningen