Correcting all Lightning explorer i18n and extract

fixes  #2533

frontend/src/app/lightning/nodes-map/nodes-map.component.html

@@ -2,7 +2,7 @@
 
   <div *ngIf="!widget" class="card-header">
     <div class="d-flex d-md-block align-items-baseline" style="margin-bottom: -5px">
-      <span i18n="lightning.nodes-world-map">Lightning nodes world map</span>
+      <span i18n="lightning.nodes-world-map">Lightning Nodes World Map</span>
     </div>
     <small style="color: #ffffff66" i18n="lightning.tor-nodes-excluded">(Tor nodes excluded)</small>
   </div>