Typo in optsecuritypage.ui

Thanks to Lionel.

Change-Id: Ib37c3cf9d8f53e941fc557dc9d4a4ba9b00e486d
Reviewed-on: https://gerrit.libreoffice.org/4056Reviewed-by: Markus Mohrhard <markus.mohrhard@googlemail.com>
Tested-by: Markus Mohrhard <markus.mohrhard@googlemail.com>

cui/uiconfig/ui/optsecuritypage.ui

@@ -139,7 +139,7 @@
                             <property name="row_spacing">6</property>
                             <child>
                               <object class="GtkCheckButton" id="usemasterpassword">
-                                <property name="label" translatable="yes">Protected _by a master passwords (recommended)</property>
+                                <property name="label" translatable="yes">Protected _by a master password (recommended)</property>
                                 <property name="visible">True</property>
                                 <property name="can_focus">True</property>
                                 <property name="receives_default">False</property>