Fixing titles and merging more i18n duplicates

frontend/src/app/components/rbf-list/rbf-list.component.html

@@ -33,7 +33,7 @@
       </div>
 
       <div class="no-replacements" *ngIf="!trees?.length">
-        <p i18n="rbf.no-replacements-yet">there are no replacements in the mempool yet!</p>
+        <p i18n="rbf.no-replacements-yet">There are no replacements in the mempool yet!</p>
       </div>
     </ng-container>
   </div>