add how to transfer data between indices

[VladimirFokow]

def transfer_data_to_index(es, ms1, ms2):
    """
    Transfer data from index 'index1' to index 'index2'
    between the timestamps `ms1` and `ms2`.
    """
    body = {
        "source": {
            "index": "index1",
            "query": {
                "range": {
                    "timestamp": {
                        "gte": ms1,
                        "lte": ms2
                    }
                }
            }
        },
        "dest": {
            "index": "index2"
        }
    }
    return es.reindex(body, refresh=True)  
    # `refresh` reindexes the index immediately, so that it can be 
    # queried and the new data will be accessible right away.

link: https://github.com/LisaHJung/Part-4-Running-Aggregations-with-Elasticsearch-and-Kibana#set-up-data-within-elasticsearch