Renamed the electrs backend support to 'electrs'.

backend/src/api/bitcoin/bitcoin-api-factory.ts

@@ -1,12 +1,12 @@
 const config = require('../../../mempool-config.json');
 import { AbstractBitcoinApi } from './bitcoin-api-abstract-factory';
 import BitcoindApi from './bitcoind-api';
-import EsploraApi from './esplora-api';
+import ElectrsApi from './electrs-api';
 
 function factory(): AbstractBitcoinApi {
   switch (config.BACKEND_API) {
-    case 'esplora':
-      return new EsploraApi();
+    case 'electrs':
+      return new ElectrsApi();
     case 'bitcoind':
     default:
       return new BitcoindApi();