global-config: new setting to disable news and change notifications...

... and also drop the version from global-config and
global-config-overlay.

doc/backup-cloud.d/notification.svg

@@ -195,7 +195,7 @@
 </tspan><tspan
          x="180"
          y="176.08282"
-         id="tspan13491">    Current:    78
+         id="tspan13491">    Version:    83
 </tspan><tspan
          x="180"
          y="191.08282"

doc/backup-upload.d/notification.svg

@@ -195,7 +195,7 @@
 </tspan><tspan
          x="180"
          y="175.85"
-         id="tspan10793">    Current:    78
+         id="tspan10793">    Version:    83
 </tspan><tspan
          x="180"
          y="190.85"

doc/check-routeros-update.d/notification.svg

@@ -211,7 +211,7 @@
 </tspan><tspan
          x="180"
          y="190.85"
-         id="tspan13565">    Current:    78</tspan></text>
+         id="tspan13565">    Version:    83</tspan></text>
     <text
        xml:space="preserve"
        id="text6580"