[DOC] Add documentation for when conditionals to Data Prepper processors

[graytaylor0]

What do you want to do?

• [ ] Request a change to existing documentation
• [X] Add new documentation
• [ ] Report a technical problem with the documentation
• [ ] Other

Tell us about your request. Provide a summary of the request and all versions that are affected. Relevant Data Prepper PR (https://github.com/opensearch-project/data-prepper/pull/2619)

Adds new parameters to the following processors grok (grok_when) parse_json (parse_when) add_entries (add_when on each entry) convert_entry_type (convert_when) copy_value (copy_when on each entry) delete_entries (delete_when) list_to_map (list_to_map_when) rename_keys (rename_when on each entry) split_string (split_when on each entry) substitute_string (substitute_when on each entry)

What other resources are available? Provide links to related issues, POCs, steps for testing, etc.

[Naarcha-AWS]

Let's transfer this over to the new Data Prepper documentation repo.

[dlvenable]

@Naarcha-AWS , We should have this in Data Prepper 2.3. I think perhaps we should add the documentation here since the new repo is not yet ready.

[hdhalter]

@graytaylor0 , @Naarcha-AWS - Has this been resolved? If not, we should transfer back to the documentation-repo so we can track it.

[dblock]

[Triage -- attendees 1, 2, 3, 4, 5, 6, 7]