[DOC] Add documentation for configuring the password hashing algorithm

[dancristiancecoi]

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• Add support for PBKDF2 for password hashing & add support for configuring BCrypt and PBKDF2 security#4524

The above changes introduces the ability to configure in the Security Plugin the password hashing algorithm and its properties.

*Version:
2.16, 3.x

[DarshitChanpura]

Coming from comment: opensearch-project/security#4524 (comment) the documentation related to the newly introduced settings should be added under Configuring OpenSearch -> Security Settings > Expert-level settings

[dancristiancecoi]

Coming from comment: opensearch-project/security#4524 (comment) the documentation related to the newly introduced settings should be added under Configuring OpenSearch -> Security Settings > Expert-level settings

Thanks @DarshitChanpura!

PR raised: #7697