fix: expose IncludeDedicatedClusterManagers in opensearch.Config

The documentation showed an example using IncludeDedicatedClusterManagers
in opensearch.Config.Transport, but this didn't work because:
- Transport expects http.RoundTripper, not opensearchtransport.Config
- IncludeDedicatedClusterManagers was only available in the low-level
  transport config, not exposed through the high-level API

Changes:
- Add IncludeDedicatedClusterManagers field to opensearch.Config
- Pass field through to transport config in NewClient()
- Fix documentation example to use the new direct configuration
- Update terminology from "cluster master" to "cluster manager"

Fixes broken documentation example and provides proper API access to
dedicated cluster manager node inclusion settings.

Signed-off-by: Sean Chittenden <sean.chittenden@crowdstrike.com>

Author: sean-

guides/node_discovery_and_roles.md

@@ -94,14 +94,12 @@ client, err := opensearch.NewClient(opensearch.Config{
     DiscoverNodesOnStart: true,
     DiscoverNodesInterval: 5 * time.Minute,
 
-    // Configure transport with cluster master exclusion
-    Transport: &opensearchtransport.Config{
-        // Default behavior (can be omitted): excludes dedicated cluster managers
-        // IncludeDedicatedClusterManagers: false,
+    // Configure cluster manager exclusion (default: false)
+    // Default behavior: excludes dedicated cluster managers
+    // IncludeDedicatedClusterManagers: false,
 
-        // To include dedicated cluster managers, set to true:
-        // IncludeDedicatedClusterManagers: true,
-    },
+    // To include dedicated cluster managers, set to true:
+    // IncludeDedicatedClusterManagers: true,
 })
 ```
 

opensearch.go

@@ -91,6 +91,13 @@ type Config struct {
 	DiscoverNodesOnStart  bool          // Discover nodes synchronously when initializing the client (blocks until complete). Default: false.
 	DiscoverNodesInterval time.Duration // Discover nodes periodically in background. Default: disabled.
 
+	// IncludeDedicatedClusterManagers includes dedicated cluster manager nodes in request routing.
+	// When false (default), dedicated cluster manager nodes are excluded from client requests,
+	// following best practices and matching the Java client's NodeSelector.SKIP_DEDICATED_CLUSTER_MASTERS behavior.
+	// When true, all nodes including dedicated cluster managers can receive client requests.
+	// Default: false (excludes dedicated cluster managers for better performance)
+	IncludeDedicatedClusterManagers bool
+
 	EnableMetrics     bool // Enable the metrics collection.
 	EnableDebugLogger bool // Enable the debug logging.
 
@@ -181,6 +188,8 @@ func NewClient(cfg Config) (*Client, error) {
 		DiscoverNodesOnStart:  cfg.DiscoverNodesOnStart,
 		DiscoverNodesInterval: cfg.DiscoverNodesInterval,
 
+		IncludeDedicatedClusterManagers: cfg.IncludeDedicatedClusterManagers,
+
 		Transport:          cfg.Transport,
 		Logger:             cfg.Logger,
 		Selector:           cfg.Selector,