Update changelog

Author: kpeeters

web2/cadabra2/source/changelog.html

@@ -18,6 +18,7 @@ <h1>Change log</h1>
 <a name="master"></a>
 <h3>github master</h3>
 <ul>
+  <li>Save command-line history (Connor).</li>
   <li>Make imported notebooks use the default <tt>post_process</t> function.</li>
   <li>Make <tt>unwrap</tt> move scalars out of exterior (wedge)
   products, see <a href="https://cadabra.science/qa/1287/collecting-scalar-terms-expressions-with-differentialforms">this