Only show electrum tab on desktop

frontend/src/app/docs/docs/docs.component.html

@@ -32,7 +32,7 @@
         </ng-template>
       </li>
 
-      <li [ngbNavItem]="3" *ngIf="showElectrsTab" role="presentation">
+      <li [ngbNavItem]="3" *ngIf="showElectrsTab" role="presentation" class="hide-on-mobile">
         <a ngbNavLink [routerLink]="['/docs/api/electrs' | relativeUrl]" role="tab">API - Electrum RPC</a>
         <ng-template ngbNavContent>
 

frontend/src/app/docs/docs/docs.component.scss

@@ -7,3 +7,9 @@
 #footer {
   clear: both;
 }
+
+@media (max-width: 992px) {
+  .hide-on-mobile {
+    display: none;
+  }
+}