Instructions unclear: how to run in AWS lambda

First off, thank you very much for building this amazing tool.

I am writing as I am having troubles running this tool in AWS lambda. I built the tool as suggested in the readme and pushed it to lambda. I also figured out through another issue (#343 ) that the main handler is `release/linux/lambda/gorush`.

But how do I know actually call it? I tried many different inputs (CLI format, API format) but nothing seems to happen actually.

One of those example formats I tried:

```
{
"notifications": [
{
"message": "value1",
"tokens": [" myTokenHere"],
"api_key": "myApiKeyHere"
}
]
}
```

And another one:

```
{
"message": "value1",
"tokens": " myTokenHere",
"api_key": "myApiKeyHere"
}
```

I even tried it how the CLI would expect it:

```
{
"m": "value1",
"t": " myTokenHere",
"k": "myApiKeyHere"
}

```

Could anybody help me please?

Start with the README’s AWS Lambda build instructions and the release/linux/lambda/gorush handler referenced in the issue. Determine which Lambda event format is accepted and document a working invocation example, including what a successful response looks like. Verify the example against the existing Lambda entry point.

Written by the indexing model from the issue text.