MAINT add Maren Westermann in the documentation team (scikit-learn#30424)

Author: glemaitre

doc/documentation_team.rst

@@ -14,6 +14,10 @@
     <p>Lucy Liu</p>
     </div>
     <div>
+    <a href='https://github.com/marenwestermann'><img src='https://avatars.githubusercontent.com/u/17019042?v=4' class='avatar' /></a> <br />
+    <p>Maren Westermann</p>
+    </div>
+    <div>
     <a href='https://github.com/Charlie-XIAO'><img src='https://avatars.githubusercontent.com/u/108576690?v=4' class='avatar' /></a> <br />
     <p>Yao Xiao</p>
     </div>