Add missing meta descriptions

frontend/src/app/components/hashrates-chart-pools/hashrate-chart-pools.component.ts

@@ -62,6 +62,7 @@ export class HashrateChartPoolsComponent implements OnInit {
     let firstRun = true;
 
     this.seoService.setTitle($localize`:@@mining.pools-historical-dominance:Pools Historical Dominance`);
+    this.seoService.setDescription($localize`:@@meta.descriptions.bitcoin.graphs.hashrate-pools:See Bitcoin mining pool dominance visualized over time: see how top mining pools' share of total hashrate has fluctuated over time.`);
     this.miningWindowPreference = this.miningService.getDefaultTimespan('6m');
     this.radioGroupForm = this.formBuilder.group({ dateSpan: this.miningWindowPreference });
     this.radioGroupForm.controls.dateSpan.setValue(this.miningWindowPreference);