Fix session dialog help link

Reviewed-By: Leena Miettinen
(cherry picked from commit 3f715252)

src/plugins/projectexplorer/sessiondialog.ui

@@ -82,7 +82,7 @@
    <item row="2" column="0" rowspan="2">
     <widget class="QLabel" name="whatsASessionLabel">
      <property name="text">
-      <string>&lt;a href=&quot;qthelp://com.nokia.qtcreator/doc/creator-quick-tour.html#session-management-in-qt-creator&quot;&gt;What is a Session?&lt;/a&gt;</string>
+      <string>&lt;a href=&quot;qthelp://com.nokia.qtcreator/doc/creator-project-managing-sessions.html&quot;&gt;What is a Session?&lt;/a&gt;</string>
      </property>
     </widget>
    </item>