capitalize Infinite tooltip in Elements panel of Math

Change-Id: I6bb19e199c1014536e967d427b966afd8ecd0302
Reviewed-on: https://gerrit.libreoffice.org/13345Reviewed-by: Wesley J. Landaker <wjl@icecavern.net>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

starmath/source/toolbox.src

@@ -1280,7 +1280,7 @@
             {
                 Identifier = RID_INFINITY ;
                 HelpId = HID_SMA_INFINITY ;
-                Text [ en-US ] = "infinite";
+                Text [ en-US ] = "Infinite";
             };
             ToolBoxItem
             {