Add block fees graph

frontend/src/app/components/graphs/graphs.component.html

@@ -16,6 +16,10 @@
         [routerLink]="['/graphs/mining/hashrate-difficulty' | relativeUrl]" i18n="mining.hashrate-difficulty">
         Hashrate & Difficulty
       </a>
+      <a class="dropdown-item" routerLinkActive="active"
+        [routerLink]="['/graphs/mining/block-fees' | relativeUrl]" i18n="mining.block-fees">
+        Block Fees
+      </a>
     </div>
   </div>
 </div>