Add failure store availability info / and port over privileges (#131729)

Author: shainaraskas

docs/reference/elasticsearch/rest-apis/api-conventions.md

@@ -421,15 +421,18 @@ GET /_nodes/ra*:2
 GET /_nodes/ra*:2*
 ```
 
-### Component Selectors [api-component-selectors]
+### Component selectors [api-component-selectors]
+```{applies_to}
+stack: ga 9.1
+```
 
 A data stream component is a logical grouping of indices that help organize data inside a data stream. All data streams contain a `data` component by default. The `data` component comprises the data stream's backing indices. When searching, managing, or indexing into a data stream, the `data` component is what you are interacting with by default.
 
 Some data stream features are exposed as additional components alongside its `data` component. These other components are comprised of separate sets of backing indices. These additional components store supplemental data independent of the data stream's regular backing indices. An example of another component is the `failures` component exposed by the data stream [failure store](docs-content://manage-data/data-store/data-streams/failure-store.md) feature, which captures documents that fail to be ingested in a separate set of backing indices on the data stream.
 
 Some APIs that accept a `<data-stream>`, `<index>`, or `<target>` request path parameter also support *selector syntax* which defines which component on a data stream the API should operate on. To use a selector, it is appended to the index or data stream name. Selectors can be combined with other index pattern syntax like [date math](#api-date-math-index-names) and wildcards.
 
-There are currently two selector suffixes supported by {{es}} APIs:
+There are two selector suffixes supported by {{es}} APIs:
 
 `::data`
 :   Refers to a data stream's backing indices containing regular data. Data streams always contain a data component.

docs/reference/elasticsearch/security-privileges.md

@@ -359,6 +359,9 @@ This section lists the privileges that you can assign to a role.
 `manage_data_stream_lifecycle`
 :   All [Data stream lifecycle](docs-content://manage-data/lifecycle/data-stream.md) operations relating to reading and managing the built-in lifecycle of a data stream. This includes operations such as adding and removing a lifecycle from a data stream.
 
+`manage_failure_store` {applies_to}`stack: ga 9.1`
+:   All `monitor` privileges plus index and data stream administration limited to failure stores only. Applies only to data streams when accessed through the [index component selector syntax](/reference/elasticsearch/rest-apis/api-conventions.md#api-component-selectors).
+
 `manage_follow_index`
 :   All actions that are required to manage the lifecycle of a follower index, which includes creating a follower index, closing it, and converting it to a regular index. This privilege is necessary only on clusters that contain follower indices.
 
@@ -388,6 +391,8 @@ This section lists the privileges that you can assign to a role.
 
     This privilege is not available in {{serverless-full}}.
 
+`read_failure_store` {applies_to}`stack: ga 9.1`
+:   Read-only access to actions performed on a data stream's failure store. Required for access to failure store data (count, explain, get, mget, get indexed scripts, more like this, multi percolate/search/termvector, percolate, scroll, clear_scroll, search, suggest, tv). Applies only to data streams when accessed through the [index component selector syntax](/reference/elasticsearch/rest-apis/api-conventions.md#api-component-selectors).
 
 `view_index_metadata`
 :   Read-only access to index and data stream metadata (aliases, exists, field capabilities, field mappings, get index, get data stream, ilm explain, mappings, search shards, settings, validate query). This privilege is available for use primarily by {{kib}} users.