[Migrated] Add on Docs: event_source from S3 with key_filters

[jneves]

Originally from: Miserlou/Zappa#1181 by ebertti

Something like this:

    {
        "function": "module.my_function",
        "event_source": {
          "arn":  "arn:aws:s3:::my-bucket",
          "key_filters": [
            {
              "type": "prefix",
              "value": "my-prefix"
            },
            {
              "type": "sufix",
              "value": ".jpg"
            }
          ],
          "events": [
            "s3:ObjectCreated:*"
          ]
        }
      }

[monkut]

released in 0.56.0, closing.