GUI: fix dark mode result table, broken by alternatecolors use + adjust prefs label

src/qtgui/uiprefs.ui

@@ -251,7 +251,7 @@
        <item>
         <widget class="QCheckBox" name="noRowJumpShortcutsCB">
          <property name="text">
-          <string>Disable the Ctrl+[0-9]/[a-z] shortcuts for jumping to table rows.</string>
+          <string>Disable the Ctrl+[0-9]/Shift+[a-z] shortcuts for jumping to table rows.</string>
          </property>
          <property name="checked">
           <bool>false</bool>

src/sampleconf/recoll-dark.qss

@@ -26,6 +26,11 @@
     selection-color: #ffffff;
 }
 
+QTableView {
+    alternate-background-color: #474747;
+    background-color: #373737;
+}
+
 QToolTip {
     background-color: yellow;
     color: black;