readme update/correct

[Lucie20]

better explain how to know the URL is broken, is this the broken link?

{
"url": "https://tvo.org/current-affairs",
"normalizedUrl": "https://tvo.org/current-affairs",
"httpStatus": null,
"errorMessage": null,
"fragment": "",
"fragmentValid": false,
"crawled": false
},

the example dataset is an old example with only a KV store

now there is anything in the KV store as described in the readme, there is only output dataset:
https://my.apify.com/tasks/hVQYNQVysl3nX4bP2#/runs/oH3FaE4wkumgG6reG

do you need proxies to run the actor? what is the consumption?