[FLINK-30436][Connectors/Opensearch][docs] Integrate Opensearch docs …

[dannycranmer]

…into Flink docs

What is the purpose of the change

Integrate Opensearch docs into Flink docs for Flink 1.16

Note This cannot be merged until Opensearch v1.0.0 tag exists

Brief change log

• See comment for pages changed

Verifying this change

Built locally and verified in browser

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changed class annotated with @Public(Evolving): no
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented? n/a

[dannycranmer]

[flinkbot]

CI report:

• 5c12008 Azure: FAILURE

Bot commands

The @flinkbot bot supports the following commands:

• @flinkbot run azure re-run the last Azure build

[reta]

Thank you very much, @dannycranmer and @MartijnVisser