Update docs with notices regarding DataPusher and scheming

The automatic uploads DataStore docs only mentioned DataPusher. We now
list all known options, recommending xloader as default, and mark
datapusher as unmaintained.

In the customizing the metadata fields tutorial, make the suggestion to
use ckanext-scheming much more prominent, and list its benefits.

doc/extensions/adding-custom-fields.rst

@@ -14,15 +14,22 @@ restrict the possible values to a defined list. By using CKAN's IDatasetForm
 plugin interface, a CKAN plugin can add custom, first-class metadata fields to
 CKAN datasets, and can do custom validation of these fields.
 
+.. warning::
+
+   In most cases users should use `ckanext-scheming <https://github.com/ckan/ckanext-scheming>`_
+   rather than the low level interfaces described in this tutorial. The ckanext-scheming
+   extension allows:
+
+      * Metadata schema configuration using a YAML or JSON schema description
+      * Automatic conversion of custom fields to the internal representation used by CKAN
+      * Automatic use of relevant template snippets according to the field type for editing and display
+      * Use of may pre-configured presets for multiple choice fields, dates, repeating subfields, etc.
+
 .. seealso::
 
    In this tutorial we are assuming that you have read the
    :doc:`/extensions/tutorial`.
 
-   You may also want to check the [ckanext-scheming](https://github.com/ckan/ckanext-scheming) 
-   extension, as it will allow metadata schema configuration using a YAML or JSON 
-   schema description, replete with custom validation and template snippets for 
-   editing and display.
 
 CKAN schemas and validation
 ---------------------------

doc/maintaining/datastore.rst

@@ -18,10 +18,10 @@ When a resource is added to the DataStore, you get:
 The DataStore is integrated into the :doc:`CKAN API </api/index>` and
 authorization system.
 
-The DataStore is generally used alongside the
-`DataPusher <https://github.com/ckan/datapusher>`_, which will
+The DataStore is generally used alongside other tools which will
 automatically upload data to the DataStore from suitable files, whether
-uploaded to CKAN's FileStore or externally linked.
+uploaded to CKAN's FileStore or externally linked. See :ref:`automatic_uploads`
+for more details.
 
 .. contents::
    :depth: 1
@@ -192,24 +192,31 @@ You can now delete the DataStore table with::
 
 To find out more about the Data API, see `The Data API`_.
 
+.. _automatic_uploads:
 
----------------------------------------------------
-DataPusher: Automatically Add Data to the DataStore
----------------------------------------------------
+------------------------------------------
+Automatically Adding Data to the DataStore
+------------------------------------------
 
-Often, one wants data that is added to CKAN (whether it is linked to or
+In most cases, you will want data that is added to CKAN (whether it is linked to or
 uploaded to the :doc:`FileStore <filestore>`) to be automatically added to the
 DataStore. This requires some processing, to extract the data from your files
 and to add it to the DataStore in the format the DataStore can handle.
 
-This task of automatically parsing and then adding data to the DataStore is
-performed by the `DataPusher`_, a service that runs asynchronously and can be installed
-alongside CKAN.
+This task of automatically parsing and then adding data to the DataStore can be performed
+by different tools, you can choose the one the best fits your requirements:
 
-To install this please look at the docs here: https://github.com/ckan/datapusher
+* `XLoader <https://github.com/ckan/ckanext-xloader>`_ is the officially supported extension for 
+  automated uploads to the DataStore. It runs as a :doc:`background job <background-tasks>` and supports
+  type guessing and limiting the number of rows imported among other settings.
+* `DataPusher+ (DataPusher Plus) <https://github.com/dathere/datapusher-plus>`_ is a next-generation replacement for the
+  DataPusher, maintained by `datHere <https://dathere.com/>`_. It focuses on increased performance and robustness and
+  includes data pre-processing capabilities to infer fields, transform data, etc.
+* `AirCan <https://github.com/datopian/aircan>`_ is a tool built on top of Apache Airflow maintained
+  by `Datopian <https://www.datopian.com/>`_ that among other functionalities supports automated data uploads to the DataStore.
+* `DataPusher <https://github.com/ckan/datapusher>`_ is a **legacy tool** that is no longer maintained.
+  It presents significant limitations so users are encouraged to migrate to one of the tools above.
 
-.. note:: The DataPusher only imports the first worksheet of a spreadsheet. It also does
-   not support duplicate column headers. That includes blank column headings.
 
 .. _data_dictionary: