qml: mempool histogram color bar: flip sign in feerate label

I think this is more intuitive as a "greater than" relation sign
than to use a signal that the label is for the leftmost point in the coloured bar.
As in, "feerates not displayed towards that direction are even higher than this value".

electrum/gui/qml/components/NetworkOverview.qml

@@ -128,7 +128,7 @@ Pane {
                         RowLayout {
                             Layout.fillWidth: true
                             Label {
-                                text: '< ' + qsTr('%1 sat/vB').arg(Math.ceil(Network.feeHistogram.max_fee))
+                                text: '> ' + qsTr('%1 sat/vB').arg(Math.ceil(Network.feeHistogram.max_fee))
                                 font.pixelSize: constants.fontSizeXSmall
                                 color: Material.accentColor
                             }