Add dedicated README for onChange email validation script

Author: Dhruvyadav2000

Client-Side Components/Catalog Client Script/Real-Time Email Validation/README.md

@@ -0,0 +1,39 @@
+# ServiceNow Email Validation - onChange Script
+
+## Overview
+Real-time email validation script for ServiceNow catalog items that provides instant feedback as users type in email fields.
+
+## Features
+- Real-time validation during user input
+- Instant error/success messages
+- Dynamic message clearing based on validity
+- User-friendly feedback with examples
+- No form submission required for validation
+
+## Implementation
+1. Navigate to **Service Catalog > Catalog Client Scripts**
+2. Click **New** to create a new script
+3. Select your **Catalog Item**
+4. Set **Type** to **onChange**
+5. Set **Variable name** to your email field variable
+6. Replace `email_field_name` with actual variable name in script
+7. Paste the script code
+8. Check **Active** checkbox
+9. Save
+
+## Validation Rules
+- Required format: `user@domain.com`
+- Accepts: letters, numbers, dots (.), underscores (_), hyphens (-)
+- Minimum 2-character top-level domain
+
+## User Experience
+- **Invalid Input**: Red error message displayed below field
+- **Valid Input**: Green info message confirming valid format
+- **Empty Field**: No validation performed
+- **While Loading**: Validation skipped to prevent false errors
+
+## Benefits
+- Immediate feedback reduces user frustration
+- Prevents errors before form submission
+- Improves data quality
+- Enhances overall user experience