Update the range queries documentation with a new example

[DawidNiezgodka]

The current example for range queries is misleading because of the possible override of records. Consider the ingestion of the following two records:

  {
    "key": 1,
    "value": {
      "userId": 1,
      "purchaseId": "abc",
      "rating": 7
    }
  }

and then:

  {
    "key": 1,
    "value": {
      "userId": 1,
      "purchaseId": "def",
      "rating": 7
    }
  }

The ingestion of the second leads to the range index for 0[...]1_0[...]7 being overwritten.
We will update the docu with an example of timestamp with the assumption of events that happen continuously and it is not possible to insert the same time for the identical key.