Update custom logs-related ingest documentation to reflect that the custom logs integration now generates an index template and pipeline

[bczifra]

Description

https://www.elastic.co/guide/en/elasticsearch/reference/8.10/ingest.html#pipelines-for-fleet-elastic-agent says:

Fleet doesn’t provide a default ingest pipeline for the Custom logs integration, but you can specify a pipeline for this integration using an index template or a custom configuration.

However, as of 2.0.0, the custom logs integration has been migrated to an Agent "input package" (type: input) and as part of that change it now creates an index template and pipeline following the data stream conventions. Given that, the quoted statement should be updated or stricken from the documentation.

[elasticsearchmachine]

Pinging @elastic/es-docs (Team:Docs)