prepare for the release of v0.2.1 (#133)

* add the missing PR number

* add a link to cf-xarray

* add back the note

* update the version number

Author: keewis

docs/examples/plotting.ipynb

@@ -52,6 +52,16 @@
     "## quantify the data"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "id": "750e0995-b0a7-4302-8780-8c3d1f2a6199",
+   "metadata": {},
+   "source": [
+    "<div class=\"alert alert-info\">\n",
+    "<strong>Note:</strong> this example uses the data provided by the <code>xarray.tutorial</code> functions. As such, the <code>units</code> attributes follow the CF conventions, which <code>pint</code> does not understand by default. To still be able to read them we are using the registry provided by <a href=\"https://github.com/xarray-contrib/cf-xarray\"><tt>cf-xarray</tt></a>.\n",
+    "</div>"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,

docs/whats-new.rst

@@ -3,18 +3,19 @@
 What's new
 ==========
 
-0.3 (*unreleased*)
-------------------
+0.2.1 (*unreleased*)
+--------------------
 - allow special "no unit" values in :py:meth:`Dataset.pint.quantify` and
   :py:meth:`DataArray.pint.quantify` (:pull:`125`)
   By `Justus Magin <https://github.com/keewis>`_.
 - convert the note about dimension coordinates saving their units in the attributes a
   warning (:issue:`124`, :pull:`126`)
   By `Justus Magin <https://github.com/keewis>`_.
 - improve the documentation on the ``format`` parameter of :py:meth:`Dataset.pint.dequantify`
-  and :py:meth:`DataArray.pint.dequantify` (:issue:`121`, :pull:`127`)
+  and :py:meth:`DataArray.pint.dequantify` (:issue:`121`, :pull:`127`, :pull:`132`)
   By `Justus Magin <https://github.com/keewis>`_.
-- use ``cf-xarray``'s unit registry in the plotting example (:issue:`107`, :pull:`128`).
+- use `cf-xarray <https://github.com/xarray-contrib/cf-xarray>`_'s unit registry in the
+  plotting example (:issue:`107`, :pull:`128`).
   By `Justus Magin <https://github.com/keewis>`_.
 
 0.2 (May 10 2021)