Custom esri token service (#1813)

* Added ability for self-hosted token service to be specified.

* Update documentation to show the available parameters

* Update pygeoapi/provider/esri.py

Co-authored-by: Benjamin Webb <40066515+webb-ben@users.noreply.github.com>

* Update pygeoapi/provider/esri.py

Co-authored-by: Benjamin Webb <40066515+webb-ben@users.noreply.github.com>

* Update pygeoapi/provider/esri.py

Co-authored-by: Benjamin Webb <40066515+webb-ben@users.noreply.github.com>

* Update pygeoapi/provider/esri.py

Co-authored-by: Benjamin Webb <40066515+webb-ben@users.noreply.github.com>

* Update pygeoapi/provider/esri.py

* Update ogcapi-features.rst

---------

Co-authored-by: Benjamin Webb <40066515+webb-ben@users.noreply.github.com>
Co-authored-by: Tom Kralidis <tomkralidis@gmail.com>

docs/source/data-publishing/ogcapi-features.rst

@@ -145,7 +145,11 @@ To publish an ESRI `Feature Service`_ or `Map Service`_ specify the URL for the
 
 * ``id_field`` will often be ``OBJECTID``, ``objectid``, or ``FID``.
 * If the map or feature service is not shared publicly, the ``username`` and ``password`` fields can be set in the
-  configuration to authenticate into the service.
+  configuration to authenticate to the service.
+* If the map or feature service is self-hosted and not shared publicly, the ``token_service`` and optional ``referer`` fields
+  can be set in the configuration to authenticate to the service.
+
+To publish from an ArcGIS online hosted service:
 
 .. code-block:: yaml
 
@@ -158,6 +162,24 @@ To publish an ESRI `Feature Service`_ or `Map Service`_ specify the URL for the
          crs: 4326 # Optional crs (default is EPSG:4326)
          username: username # Optional ArcGIS username
          password: password # Optional ArcGIS password
+         token_service: https://your.server.com/arcgis/sharing/rest/generateToken  # optional URL to your generateToken service
+         referer: https://your.server.com  # optional referer, defaults to https://www.arcgis.com if not set
+
+To publish from a self-hosted service that is not publicly accessible, the ``token_service`` field is required:
+
+.. code-block:: yaml
+
+   providers:
+       - type: feature
+         name: ESRI
+         data: https://your.server.com/arcgis/rest/services/your-layer/MapServer/0
+         id_field: objectid
+         time_field: date_in_your_device_time_zone # Optional time field
+         crs: 4326 # Optional crs (default is EPSG:4326)
+         username: username # Optional ArcGIS username
+         password: password # Optional ArcGIS password
+         token_service: https://your.server.com/arcgis/sharing/rest/generateToken # Optional url to your generateToken service
+         referer: https://your.server.com # Optional referer, defaults to https://www.arcgis.com if not set
 
 GeoJSON
 ^^^^^^^