Document HA for Access Request plugins

docs/pages/access-controls/access-request-plugins/index.mdx

@@ -6,7 +6,33 @@ layout: tocless-doc
 
 Teleport Just-in-Time Access Requests allow users to receive temporary elevated
 privileges by seeking consent from one or more reviewers, depending on your
-configuration. 
+configuration.
+
+With Teleport's Access Request plugins, users can manage Access Requests from
+within your organization's existing messaging and project management solutions.
+
+## Plugin guides
 
 (!docs/pages/includes/access-request-integrations.mdx!)
 
+## Architecture
+
+Access Request plugins are self-contained programs that connect to the Teleport
+Auth Service's gRPC API to listen for audit events relating to new or updated
+Access Requests. After processing an Access Request event, Access Request plugins
+interact with a third-party API (e.g., the Slack or PagerDuty APIs). 
+
+Access Request plugins can run within private networks that are isolated from
+the Teleport Auth Service. To access the Auth Service API, they connect to the
+Proxy Service, which establishes a reverse tunnel for the plugin to access the
+Auth Service.
+
+You can run multiple instances of an Access Request plugin for high availability
+by deploying each instance in a separate availability zone. There is no need for
+additional configuration or load balancing, as plugins avoid creating duplicate
+requests to their third-party APIs.
+
+To read more about the architecture of an Access Request plugin, and start
+writing your own, read our [Access Request plugin development
+guide](../../api/access-plugin.mdx).
+

docs/pages/access-controls/access-requests/resource-requests.mdx

@@ -571,6 +571,10 @@ the requested node, the hostname will be displayed in the Review Request page of
 the Teleport Web UI.
 
 ### Integrating with an external tool
+
+With Teleport's Access Request plugins, users can manage Access Requests from
+within your organization's existing messaging and project management solutions.
+
 (!docs/pages/includes/access-request-integrations.mdx!)
 
 ### Using TTLs with Access Requests

docs/pages/access-controls/access-requests/role-requests.mdx

@@ -154,6 +154,10 @@ to the original set of roles.
 ## Next Steps
 
 ### Integrating with an external tool
+
+With Teleport's Access Request plugins, users can manage Access Requests from
+within your organization's existing messaging and project management solutions.
+
 (!docs/pages/includes/access-request-integrations.mdx!)
 
 ### Advanced RBAC

docs/pages/includes/access-request-integrations.mdx

@@ -1,7 +1,3 @@
-With Teleport's Access Request plugins, users can request,
-approve, and deny access without leaving your organization's existing messaging
-and project management solutions.
-
 | Integration | Type | Setup Instructions |
 | - | - | - |
 | Slack | Messaging | [Set up Slack](../access-controls/access-request-plugins/ssh-approval-slack.mdx) |