Document new ingest and search pipeline allowlist settings

_ingest-pipelines/processors/index-processors.md

@@ -71,3 +71,7 @@ Processor type | Description
 ## Batch-enabled processors
 
 Some processors support batch ingestion---they can process multiple documents at the same time as a batch. These batch-enabled processors usually provide better performance when using batch processing. For batch processing, use the [Bulk API]({{site.url}}{{site.baseurl}}/api-reference/document-apis/bulk/) and provide a `batch_size` parameter. All batch-enabled processors have a batch mode and a single-document mode. When you ingest documents using the `PUT` method, the processor functions in single-document mode and processes documents in series. Currently, only the `text_embedding` and `sparse_encoding` processors are batch enabled. All other processors process documents one at a time.
+
+## Selectively enabling processors
+
+Processors defined by the [ingest-common module](https://github.com/opensearch-project/OpenSearch/blob/2.x/modules/ingest-common/src/main/java/org/opensearch/ingest/common/IngestCommonPlugin.java) can be selectively enabled by providing the static cluster setting `ingest-common.processors.allowed`. If not specified, then all processors are enabled by default. If an empty list is specified, then all processors are disabled. If the setting is changed to remove previously-enabled processors, then any pipeline using a disabled processor will fail after the node is restarted and the new setting takes effect.

_search-plugins/search-pipelines/search-processors.md

@@ -121,3 +121,7 @@ The response contains the `search_pipelines` object that lists the available req
 
 In addition to the processors provided by OpenSearch, additional processors may be provided by plugins.
 {: .note}
+
+## Selectively enabling processors
+
+Processors defined by the [search-pipeline-common module](https://github.com/opensearch-project/OpenSearch/blob/2.x/modules/search-pipeline-common/src/main/java/org/opensearch/search/pipeline/common/SearchPipelineCommonModulePlugin.java) can be selectively enabled by providing the following static cluster settings: `search.pipeline.common.request.processors.allowed`, `search.pipeline.common.response.processors.allowed`, or `search.pipeline.common.search.phase.results.processors.allowed`. If not specified, then all processors are enabled by default. If an empty list is specified, then all processors are disabled. If the setting is changed to remove previously-enabled processors, then any pipeline using a disabled processor will fail after the node is restarted and the new setting takes effect.