Mention that this is about *toolbar* icon size

Change-Id: Id48edf2677d6adc31983ca21e248447af9a58a23
Reviewed-on: https://gerrit.libreoffice.org/26859Reviewed-by: Samuel Mehrbrodt <Samuel.Mehrbrodt@cib.de>
Tested-by: Samuel Mehrbrodt <Samuel.Mehrbrodt@cib.de>

cui/uiconfig/ui/optviewpage.ui

@@ -337,7 +337,7 @@
                             <property name="visible">True</property>
                             <property name="can_focus">False</property>
                             <property name="halign">end</property>
-                            <property name="label" translatable="yes">Icon _size:</property>
+                            <property name="label" translatable="yes">Toolbar icon _size:</property>
                             <property name="use_underline">True</property>
                             <property name="mnemonic_widget">iconsize</property>
                           </object>