Enhance docs book integration with feature gates documentation

Author: wazery

docs/book/src/reference/markers/feature-gates.md

@@ -2,6 +2,34 @@
 
 Feature gates allow you to enable or disable experimental features in your Kubebuilder controllers. This is similar to how Kubernetes core uses feature gates to manage experimental functionality.
 
+## Quick Start
+
+### Marking Fields
+
+```go
+type MyResourceSpec struct {
+    // Standard field
+    Name string `json:"name"`
+
+    // Experimental field
+    // +feature-gate experimental-bar
+    Bar *string `json:"bar,omitempty"`
+}
+```
+
+### Running with Feature Gates
+
+```bash
+# Enable feature gates
+./manager --feature-gates=experimental-bar
+
+# Multiple gates
+./manager --feature-gates=experimental-bar,advanced-features
+
+# Mixed states
+./manager --feature-gates=experimental-bar=true,advanced-features=false
+```
+
 ## Overview
 
 Feature gates provide a mechanism to:
@@ -55,10 +83,10 @@ The `--feature-gates` flag accepts:
 ### Naming Conventions
 
 Use descriptive, lowercase names with hyphens:
-- ✅ `experimental-bar`
-- ✅ `advanced-features`
-- ❌ `ExperimentalBar`
-- ❌ `advanced_features`
+- `experimental-bar`
+- `advanced-features`
+- `ExperimentalBar`
+- `advanced_features`
 
 ### Documentation
 
@@ -133,4 +161,26 @@ Enable debug logging to see feature gate discovery:
 
 ```bash
 ./manager --feature-gates=experimental-bar --zap-log-level=debug
-``` 
+```
+
+## Implementation Status
+
+### Production Ready
+
+- Feature gate discovery and validation
+- Controller integration with `--feature-gates` flag
+- Scaffolding integration for new projects
+
+### Future Enhancement
+
+- CRD schema modification (requires [controller-tools support](https://github.com/kubernetes-sigs/controller-tools/issues/1238))
+
+When [controller-tools supports feature gates](https://github.com/kubernetes-sigs/controller-tools/issues/1238), you'll be able to use:
+
+```go
+// +kubebuilder:feature-gate=experimental-bar
+// +optional
+Bar *string `json:"bar,omitempty"`
+```
+
+This will automatically exclude the field from CRD schemas when the feature gate is disabled. 

pkg/machinery/featuregate.go

@@ -5,7 +5,7 @@ Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at
 
-    http://www/apache.org/licenses/LICENSE-2.0
+    http://www.apache.org/licenses/LICENSE-2.0
 
 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,

pkg/plugins/golang/v4/scaffolds/internal/templates/cmd/main.go

@@ -269,7 +269,7 @@ func main() {
 	var metricsAddr string
 	var metricsCertPath, metricsCertName, metricsCertKey string
 	var webhookCertPath, webhookCertName, webhookCertKey string
-		var enableLeaderElection bool
+	var enableLeaderElection bool
 	var probeAddr string
 	var secureMetrics bool
 	var enableHTTP2 bool
@@ -280,7 +280,7 @@ func main() {
 	flag.StringVar(&probeAddr, "health-probe-bind-address", ":8081", "The address the probe endpoint binds to.")
 	flag.BoolVar(&enableLeaderElection, "leader-elect", false,
 		"Enable leader election for controller manager. " +
-			"Enabling this will ensure there is only one active controller manager.")
+		"Enabling this will ensure there is only one active controller manager.")
 	flag.BoolVar(&secureMetrics, "metrics-secure", true,
 		"If set, the metrics endpoint is served securely via HTTPS. Use --metrics-secure=false to use HTTP instead.")
 	flag.StringVar(&webhookCertPath, "webhook-cert-path", "", "The directory that contains the webhook certificate.")