title: Changing elasticsearch index's shard-count on the next index-rotation
body: <p>I have an ELK (Elasticsearch-Kibana) stack wherein the elasticsearch node has the default shard value of 5. Logs are pushed to it in logstash format (<code>logstash-YYYY.MM.DD</code>), which - correct me if I am wrong - are indexed date-wise.</p>
  <p>Since I cannot change the shard count of an existing index without reindexing, I want to increase the number of shards to 8 when <em>the next index is created</em>. I figured that the ES-API allows on-the-fly persistent changes.</p>
  <p>How do I go about doing this?</p>