feat: Add nginx example to demonstrate helm-values-manager usage

- Add example using Bitnami nginx chart
- Demonstrate value management for staging and production
- Show validation capabilities
- Include cleanup instructions and .gitignore
- Focus on simplified configuration for clarity

Author: ritwik-g

example/nginx/.gitignore

@@ -0,0 +1,13 @@
+# Generated value files
+*.nginx-app.values.yaml
+
+# Generated manifest files
+*-manifests.yaml
+
+# Helm Values Manager files
+helm-values.json
+.helm-values.lock
+
+# Temporary files that might be created during development
+*.tmp
+*.bak

example/nginx/README.md

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+# Helm Values Manager Example
+
+This example demonstrates how to use the helm-values-manager plugin to manage different configurations for staging and production environments using the Bitnami Nginx chart.
+
+## Reference Values
+
+Here are the reference values that we'll be managing across environments:
+
+### Base Values (common.yaml)
+
+```yaml
+nginx:
+  image:
+    registry: docker.io
+    repository: bitnami/nginx
+    tag: latest
+    pullPolicy: IfNotPresent
+```
+
+### Staging Values (staging.yaml)
+
+```yaml
+nginx:
+  replicaCount: 1
+
+  service:
+    type: ClusterIP
+    port: 80
+
+  ingress:
+    enabled: true
+    hostname: staging.example.com
+
+  metrics:
+    enabled: false
+```
+
+### Production Values (production.yaml)
+
+```yaml
+nginx:
+  replicaCount: 3
+
+  service:
+    type: LoadBalancer
+    port: 80
+
+  ingress:
+    enabled: true
+    hostname: example.com
+    tls: true
+
+  metrics:
+    enabled: true
+```
+
+## Setup and Usage
+
+1. Add the Bitnami repository:
+
+```bash
+helm repo add bitnami https://charts.bitnami.com/bitnami
+helm repo update
+```
+
+2. Initialize helm-values-manager for the nginx release:
+
+```bash
+helm values-manager init --release nginx-app
+```
+
+3. Add value configurations with descriptions and validation:
+
+```bash
+# Core configurations
+helm values-manager add-value-config --path nginx.replicaCount --description "Number of nginx replicas" --required
+helm values-manager add-value-config --path nginx.service.type --description "Kubernetes service type (ClusterIP/LoadBalancer)" --required
+helm values-manager add-value-config --path nginx.service.port --description "Service port number" --required
+
+# Ingress configuration
+helm values-manager add-value-config --path nginx.ingress.enabled --description "Enable ingress" --required
+helm values-manager add-value-config --path nginx.ingress.hostname --description "Ingress hostname"
+helm values-manager add-value-config --path nginx.ingress.tls --description "Enable TLS for ingress"
+
+# Metrics configuration
+helm values-manager add-value-config --path nginx.metrics.enabled --description "Enable prometheus metrics"
+```
+
+4. Add deployments for different environments:
+
+```bash
+helm values-manager add-deployment staging
+helm values-manager add-deployment production
+```
+
+5. Set values for staging environment:
+
+```bash
+# Basic configuration
+helm values-manager set-value --path nginx.replicaCount --value 1 --deployment staging
+helm values-manager set-value --path nginx.service.type --value ClusterIP --deployment staging
+helm values-manager set-value --path nginx.service.port --value 80 --deployment staging
+
+# Ingress configuration
+helm values-manager set-value --path nginx.ingress.enabled --value true --deployment staging
+helm values-manager set-value --path nginx.ingress.hostname --value staging.example.com --deployment staging
+
+# Metrics configuration
+helm values-manager set-value --path nginx.metrics.enabled --value false --deployment staging
+```
+
+6. Generate staging values:
+
+```bash
+# Generate staging values - this should succeed as all required values are set
+helm values-manager generate --deployment staging
+```
+
+7. Set up production environment (demonstrating validation):
+
+```bash
+# Set some of the production values, intentionally omitting service configuration
+helm values-manager set-value --path nginx.replicaCount --value 3 --deployment production
+helm values-manager set-value --path nginx.ingress.enabled --value true --deployment production
+helm values-manager set-value --path nginx.ingress.hostname --value example.com --deployment production
+helm values-manager set-value --path nginx.ingress.tls --value true --deployment production
+helm values-manager set-value --path nginx.metrics.enabled --value true --deployment production
+
+# Try to generate values - this should fail with validation errors
+helm values-manager generate --deployment production
+```
+
+The above command will fail with validation errors because we haven't set two required values:
+
+1. `nginx.service.type`
+2. `nginx.service.port`
+
+This demonstrates how helm-values-manager helps catch missing configurations early in the deployment process.
+
+8. Fix validation errors and complete production setup:
+
+```bash
+# Set the missing required values
+helm values-manager set-value --path nginx.service.type --value LoadBalancer --deployment production
+helm values-manager set-value --path nginx.service.port --value 80 --deployment production
+
+# Now the generate command should succeed
+helm values-manager generate --deployment production
+```
+
+9. Verify configurations using helm template:
+
+```bash
+# Template the chart for staging environment
+helm template nginx-staging bitnami/nginx -f common.yaml -f staging.nginx-app.values.yaml
+
+# Template the chart for production environment
+helm template nginx-prod bitnami/nginx -f common.yaml -f prod.nginx-app.values.yaml
+
+# You can also save the templated output to files for inspection
+helm template nginx-staging bitnami/nginx -f common.yaml -f staging.nginx-app.values.yaml > staging-manifests.yaml
+helm template nginx-prod bitnami/nginx -f common.yaml -f prod.nginx-app.values.yaml > prod-manifests.yaml
+```
+
+The helm template command will show you the actual Kubernetes manifests that would be created, allowing you to:
+
+- Verify that all values are correctly applied
+- Inspect the differences between environments
+- Catch any issues before actual deployment
+
+## Key Benefits Demonstrated
+
+1. **Configuration Validation**: Early detection of missing or invalid configurations through required value definitions
+2. **Value Documentation**: Each configuration value is documented with clear descriptions
+3. **Environment Separation**: Clean separation between staging and production configurations
+4. **Structured Management**: Organized way to add and modify values
+5. **Value Tracking**: Easy to track what values are available and required
+
+## Cleanup
+
+To clean up the example:
+
+1. Remove generated value files:
+
+```bash
+rm -f *.nginx-app.values.yaml
+```
+
+2. Remove generated manifest files:
+
+```bash
+rm -f *-manifests.yaml
+```
+
+3. Remove helm-values-manager files:
+
+```bash
+rm -f helm-values.json .helm-values.lock
+```

example/nginx/common.yaml

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+nginx:
+  image:
+    registry: docker.io
+    repository: bitnami/nginx
+    tag: latest
+    pullPolicy: IfNotPresent
+
+  serverBlock: ""
+
+  metrics:
+    enabled: false