fix(readme): fix readme

readme.md

@@ -36,7 +36,7 @@ This class provides scheduling of functions with a cron syntax
 ```typescript
 import { CronManager } from '@pushrocks/smarrtime';
 const cronManagerInstance = new CronManager();
-cronManagerInstance.addConrjob('* * * * * *', async () => {
+cronManagerInstance.addCronjob('* * * * * *', async () => {
   console.log('hello'); // will log 'hello' to console once every second;
 });
 cronManagerInstance.start();