update readme

Author: butschster

README.md

@@ -447,6 +447,184 @@ The generated schema will include a `oneOf` section to reflect the union types:
 > All supported types are automatically resolved from native PHP type declarations and reflected in the JSON Schema
 > output using oneOf.
 
+## Constraint Attributes
+
+Generator supports dedicated constraint attributes that provide a clean, modular approach to validation rules.
+
+### Available Constraint Attributes
+
+#### String Constraints
+
+- `#[Pattern(regex)]` - Regular expression pattern validation
+- `#[Length(min, max)]` - String length constraints
+
+#### Numeric Constraints
+
+- `#[Range(min, max, exclusiveMin, exclusiveMax)]` - Numeric range validation with optional exclusive bounds
+- `#[MultipleOf(value)]` - Multiple of validation for numbers
+
+#### Array Constraints
+
+- `#[Items(min, max, unique)]` - Array item constraints with optional uniqueness
+- `#[Length(min, max)]` - Array length constraints (same attribute as strings, auto-detects type)
+
+#### General Constraints
+
+- `#[Enum(values)]` - Enumeration validation with array of allowed values
+
+### Usage Examples
+
+#### String Validation
+
+```php
+namespace App\DTO;
+
+use Spiral\JsonSchemaGenerator\Attribute\Field;
+use Spiral\JsonSchemaGenerator\Attribute\Constraint\Pattern;
+use Spiral\JsonSchemaGenerator\Attribute\Constraint\Length;
+
+final readonly class User
+{
+    public function __construct(
+        #[Field(title: 'Full Name', description: 'User full name in Title Case')]
+        #[Pattern('^[A-Z][a-z]+(?: [A-Z][a-z]+)*$')]
+        #[Length(min: 2, max: 100)]
+        public string $name,
+
+        #[Field(title: 'Username')]
+        #[Pattern('^[a-zA-Z0-9_]{3,20}$')]
+        #[Length(min: 3, max: 20)]
+        public string $username,
+
+        #[Field(title: 'Email', format: Format::Email)]
+        #[Pattern('^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\\.[a-zA-Z]{2,}$')]
+        public string $email,
+    ) {}
+}
+```
+
+#### Numeric Validation
+
+```php
+namespace App\DTO;
+
+use Spiral\JsonSchemaGenerator\Attribute\Field;
+use Spiral\JsonSchemaGenerator\Attribute\Constraint\Range;
+use Spiral\JsonSchemaGenerator\Attribute\Constraint\MultipleOf;
+
+final readonly class Product
+{
+    public function __construct(
+        #[Field(title: 'Price', description: 'Product price in USD')]
+        #[Range(min: 0.01, max: 99999.99)]
+        #[MultipleOf(0.01)]
+        public float $price,
+
+        #[Field(title: 'Stock Quantity')]
+        #[Range(min: 0, max: 10000)]
+        public int $stock,
+
+        #[Field(title: 'Discount Percentage')]
+        #[Range(min: 0, max: 100, exclusiveMax: true)]
+        public float $discountPercent,
+    ) {}
+}
+```
+
+#### Array and Enum Validation
+
+```php
+namespace App\DTO;
+
+use Spiral\JsonSchemaGenerator\Attribute\Field;
+use Spiral\JsonSchemaGenerator\Attribute\Constraint\Items;
+use Spiral\JsonSchemaGenerator\Attribute\Constraint\Length;
+use Spiral\JsonSchemaGenerator\Attribute\Constraint\Enum;
+
+final readonly class BlogPost
+{
+    public function __construct(
+        #[Field(title: 'Tags', description: 'Post tags')]
+        #[Items(min: 1, max: 10, unique: true)]
+        public array $tags,
+
+        #[Field(title: 'Categories', description: 'Post categories')]
+        #[Length(min: 1, max: 5)]
+        public array $categories,
+
+        #[Field(title: 'Status')]
+        #[Enum(['draft', 'published', 'archived', 'pending'])]
+        public string $status,
+
+        #[Field(title: 'Priority')]
+        #[Enum([1, 2, 3, 4, 5])]
+        public int $priority,
+    ) {}
+}
+```
+
+### Generated Schema Output
+
+The constraint attributes generate clean, standards-compliant JSON Schema validation rules:
+
+```json
+{
+  "type": "object",
+  "properties": {
+    "name": {
+      "title": "Full Name",
+      "description": "User full name in Title Case",
+      "type": "string",
+      "pattern": "^[A-Z][a-z]+(?: [A-Z][a-z]+)*$",
+      "minLength": 2,
+      "maxLength": 100
+    },
+    "price": {
+      "title": "Price",
+      "description": "Product price in USD",
+      "type": "number",
+      "minimum": 0.01,
+      "maximum": 99999.99,
+      "multipleOf": 0.01
+    },
+    "tags": {
+      "title": "Tags",
+      "description": "Post tags",
+      "type": "array",
+      "minItems": 1,
+      "maxItems": 10,
+      "uniqueItems": true
+    },
+    "status": {
+      "title": "Status",
+      "type": "string",
+      "enum": [
+        "draft",
+        "published",
+        "archived",
+        "pending"
+      ]
+    }
+  },
+  "required": [
+    "name",
+    "price",
+    "tags",
+    "status"
+  ]
+}
+```
+
+### Type Safety
+
+Constraint attributes are automatically validated for type compatibility:
+
+- `Pattern` only applies to string properties
+- `Range` and `MultipleOf` only apply to numeric properties (int, float)
+- `Items` constraints only apply to array properties
+- `Length` adapts behavior: `minLength`/`maxLength` for strings, `minItems`/`maxItems` for arrays
+- `Enum` works with any property type
+
 ## PHPDoc Validation Constraints
 
 Generator supports extracting validation constraints from PHPDoc comments, providing rich validation