Add copyright to README and remove year from NOTICE

[dblock]

See opensearch-project/.github#21

[dblock]

Also is NOTICE correct? Does this project contain Elastic Code?

[krishna-ggk]

Noting example - https://github.com/opensearch-project/.github/pull/24/files

[soosinha]

@dblock The plugin itself does not contain Elastic code. But it depends on OpenSearch libraries which has Elastic code. So is it fine to remove the Elastic copyright from NOTICE ?

[dblock]

@dblock The plugin itself does not contain Elastic code. But it depends on OpenSearch libraries which has Elastic code. So is it fine to remove the Elastic copyright from NOTICE ?

Yes.

The same goes for other Apache code notice. Unless you know of a specific instance where you've picked up code that had a copyright notice for Apache Software Foundation (vs. just licensed under APLv2), you should remove it as well.