docs: config validation (#80)

Documentation for enabling config schema validation

---

### **Checklist**
- [x] Documentation updated (if needed)
- [x] Code conforms to style guidelines

---------

Signed-off-by: Roaa Sakr <romoh@microsoft.com>

docs/imagecustomizer/how-to/vscode-schema-validation.md

@@ -0,0 +1,54 @@
+# Enabling VS Code Configuration Validation for Prism (Image Customizer)
+
+This guide explains how to set up YAML validation in Visual Studio Code (VS
+Code) for authoring image customization configurations.
+
+## Prerequisites
+
+- VS Code installed on your system.
+
+## Steps to Enable Validation
+
+### 1. Install the YAML Extension
+
+Download and install [YAML VS Code
+extension](https://marketplace.visualstudio.com/items?itemName=redhat.vscode-yaml).
+This extension provides YAML validation and syntax highlighting.
+
+### 2. Update VS Code Settings
+
+Modify your VS Code `settings.json` to point to the schema corresponding to the
+version of Prism you are using.
+
+Add the following to your `settings.json` file after updating `<RELEASE>` and
+`<SPECIFIC-FOLDER>`:
+
+- `<SPECIFIC-FOLDER>` is the directory containing your image configs.
+- `<RELEASE>` is the version of Image Customizer that you are using (e.g.: v0.8).
+
+```json
+"yaml.schemas": {
+    "https://raw.githubusercontent.com/microsoft/azure-linux-image-tools/release/<RELEASE>/toolkit/tools/imagecustomizerapi/schema.json": [
+        "<SPECIFIC-FOLDER>/**/*.yaml"
+    ]
+}
+```
+
+For example:
+
+```json
+"yaml.schemas": {
+    "https://raw.githubusercontent.com/microsoft/azure-linux-image-tools/release/v0.9/toolkit/tools/imagecustomizerapi/schema.json": [
+        "/home/test/image-configs/**/*.yaml"
+    ]
+}
+```
+
+### 3. Validate Configurations
+
+Once configured, YAML files in the specified directory will automatically be
+validated against the schema. This enables syntax highlighting for errors and
+provides instant feedback while editing your configurations. It ensures your
+YAML files are properly formatted and conform to the schema.
+
+You’re now ready to go!