More clarity on setting iris-test-data location.

docs/src/developers_guide/contributing_running_tests.rst

@@ -20,10 +20,13 @@ A separate repository under the `SciTools`_ organisation is used, see
 https://github.com/SciTools/iris-test-data.
 
 In order to run the tests with **all** the test data you must clone the
-``iris-test-data`` repository and then configure your shell to ensure the Iris
-tests can find it by using the shell environment variable named
-**OVERRIDE_TEST_DATA_REPOSITORY**.  The example command below uses
-``~/projects`` as the parent directory::
+``iris-test-data`` repository and then ensure the Iris tests can access
+``iris-test-data/test_data``, using one of two methods:
+
+* Store the path in a shell environment variable named **OVERRIDE_TEST_DATA_REPOSITORY**.
+* Store the path in ``lib/iris/etc/site.cfg`` (see :mod:`iris.config` for more).
+
+The example command below uses ``~/projects`` as the parent directory::
 
    cd ~/projects
    git clone [email protected]:SciTools/iris-test-data.git

docs/src/whatsnew/latest.rst

@@ -130,6 +130,9 @@ This document explains the changes made to Iris for this release
    :class:`iris.Constraint` to :ref:`userguide loading section
    <constrained-loading>` and to api reference documentation. (:pull:`4321`)
 
+#. `@trexfeathers`_ added more detail on making `iris-test-data`_ available
+   during :ref:`developer_running_tests`. (:pull:`4359`)
+
 
 💼 Internal
 ===========

lib/iris/config.py

@@ -8,7 +8,7 @@
 
 The default configuration values can be overridden by creating the file
 ``iris/etc/site.cfg``. If it exists, this file must conform to the format
-defined by :mod:`ConfigParser`.
+defined by :mod:`configparser`.
 
 ----------