docs: add README for renovate presets

.github/workflows/validate-renovate-config.yml

@@ -21,7 +21,7 @@ jobs:
           files: |
             renovate.json
             default.json
-            renovate-presets/**
+            renovate-presets/**/*.{json,json5}
           matrix: true
 
   validate-renovate-configs:

renovate-presets/README.md

@@ -0,0 +1,112 @@
+# Renovate Presets
+
+This directory contains shareable Renovate configuration presets that can be used across multiple repositories in your organization. The presets can be added to the `renovate.json` file in the `extends` block.
+
+## Available Presets
+
+### branch-merge.json
+
+**Purpose**: Enables automatic branch merging for low-risk updates during business hours.
+
+**Features**:
+- Automatically merges minor, patch, and digest updates
+- Operates on Berlin timezone (Europe/Berlin)
+- Merge window: Monday-Friday, 9:00-13:00
+- Uses branch automerge strategy (merges without creating PRs)
+
+**Usage**:
+```json
+{
+  "extends": [
+    "github>leanix/.github//renovate-presets/branch-merge.json"
+  ]
+}
+```
+
+**When to use**:
+- Repositories with comprehensive test coverage
+- Projects where minor/patch updates are considered safe
+- Teams that want to reduce PR noise for routine updates
+
+### security.json5
+
+> [!NOTE]
+> This preset is part of the LeanIX renovate preset
+
+**Purpose**: Integrates OSV (Open Source Vulnerabilities) database to enhance security monitoring.
+
+**Features**:
+- Displays OSV vulnerability alerts in the Renovate dependency dashboard
+- Enables OSV vulnerability scanning for all dependencies (experimental feature)
+- Provides comprehensive vulnerability information from the [OSV database](https://osv.dev/)
+
+**Usage**:
+```json
+{
+  "extends": [
+    "github>leanix/.github//renovate-presets/security.json5"
+  ]
+}
+```
+
+**When to use**:
+- All repositories that want enhanced security vulnerability detection
+- Projects that need to comply with security standards
+- Teams that want proactive security alerts beyond standard vulnerability databases
+
+## Default Preset
+
+The main [default.json](../default.json) preset in the repository root provides organization-wide defaults:
+
+**Features**:
+- Best practices configuration from Renovate
+- Pin all dependencies except peer dependencies
+- 5-day minimum release age for stability (with timestamp-optional fallback)
+- Strict internal checks
+- Custom package rules:
+  - Excludes legacy Kubernetes client versions
+  - Restricts Liquibase to versions below 5.0
+  - Bypasses minimum release age for internal `@leanix/*` packages
+
+**Usage**:
+```json
+{
+  "extends": [
+    "github>leanix/.github"
+  ]
+}
+```
+
+This automatically applies the default configuration and security preset.
+
+## Combining Presets
+
+You can combine multiple presets to build your ideal configuration:
+
+```json
+{
+  "$schema": "https://docs.renovatebot.com/renovate-schema.json",
+  "extends": [
+    "github>leanix/.github",
+    "github>leanix/.github//renovate-presets/branch-merge.json"
+  ]
+}
+```
+
+This example inherits the organization defaults and adds automatic branch merging for minor/patch updates.
+
+## Creating Custom Presets
+
+To add a new preset:
+
+1. Create a new `.json` or `.json5` file in this directory
+2. Define your Renovate configuration options
+3. Document the preset in this README
+4. Reference it using: `github>leanix/.github//renovate-presets/<filename>`
+
+## Resources
+
+- [Renovate Documentation](https://docs.renovatebot.com/)
+- [Config Presets](https://docs.renovatebot.com/config-presets/)
+- [OSV Database](https://osv.dev/)
+- [Shareable Config Presets](https://docs.renovatebot.com/config-presets/#github)