Fix name typo in the UI option

Author: MohamedAlmaki

qt/widgets/common/inc/MantidQtWidgets/Common/SequentialFitDialog.ui

@@ -181,7 +181,7 @@
         <bool>false</bool>
        </property>
        <property name="text">
-        <string>Output spectrum vs params</string>
+        <string>Output workspace index vs params</string>
        </property>
       </widget>
      </item>