Add meta descriptions for mempool and liquid

frontend/src/app/components/block-fees-graph/block-fees-graph.component.ts

@@ -65,6 +65,7 @@ export class BlockFeesGraphComponent implements OnInit {
 
   ngOnInit(): void {
     this.seoService.setTitle($localize`:@@6c453b11fd7bd159ae30bc381f367bc736d86909:Block Fees`);
+    this.seoService.setDescription($localize`:@@meta.description.bitcoin.graphs.block-fees:See the average mining fees earned per Bitcoin block visualized in BTC and USD over time.`);
     this.miningWindowPreference = this.miningService.getDefaultTimespan('1m');
     this.radioGroupForm = this.formBuilder.group({ dateSpan: this.miningWindowPreference });
     this.radioGroupForm.controls.dateSpan.setValue(this.miningWindowPreference);
@@ -192,7 +193,7 @@ export class BlockFeesGraphComponent implements OnInit {
           {
             name: 'Fees ' + this.currency,
             inactiveColor: 'rgb(110, 112, 121)',
-            textStyle: {  
+            textStyle: {
               color: 'white',
             },
             icon: 'roundRect',