Update README.md (#5)

README.md

@@ -5,6 +5,9 @@
 [![Codecov](https://codecov.io/gh/cycle/orm-promise-mapper/graph/badge.svg)](https://codecov.io/gh/cycle/orm-promise-mapper)
 <a href="https://discord.gg/TFeEmCs"><img src="https://img.shields.io/badge/discord-chat-magenta.svg"></a>
 
+Cycle ORM provides the ability to carry data over the specific class instances by using `cycle/orm-promise-mapper`
+package with `\Cycle\ORM\Reference\Promise` objects for relations with lazy loading.
+
 ## Installation
 
 The preferred way to install this package is through [Composer](https://getcomposer.org/download/):
@@ -13,6 +16,66 @@ The preferred way to install this package is through [Composer](https://getcompo
 composer require cycle/orm-promise-mapper
 ```
 
+## Define the Entity
+
+```php
+use Cycle\Annotated\Annotation\Entity;
+use Cycle\Annotated\Annotation\Column;
+use Cycle\Annotated\Annotation\Relation\BelongsTo;
+use Cycle\Annotated\Annotation\Relation\HasMany;
+use Cycle\ORM\Reference\ReferenceInterface;
+
+#[Entity]
+class User
+{
+    #[Column(type: 'primary')]
+    public int $id;
+
+    #[HasMany(target: Post::class, load: 'eager')]
+    public array $posts;
+
+    #[HasMany(target: Tag::class, load: 'lazy')]
+    public ReferenceInterface|array $tags;
+}
+
+#[Entity]
+class Post
+{
+    // ...
+
+    #[BelongsTo(target: User::class, load: 'lazy')]
+    public ReferenceInterface|User $user;
+
+    #[BelongsTo(target: Tag::class, load: 'eager')]
+    public Tag $tag;
+}
+```
+
+## Fetching entity data
+
+```php
+$user = $orm->getRepository('user')->findByPK(1);
+
+// $user->posts contains an array because of eager loading
+foreach ($user->posts as $post) {
+    // ...
+}
+
+// $user->tags contains Cycle\ORM\Reference\Promise object because of lazy loading
+$tags = $user->tags->fetch();
+foreach ($tags as $post) {
+    // ...
+}
+
+$post = $orm->getRepository('post')->findByPK(1);
+
+// $post->user contains Cycle\ORM\Reference\Promise object because of lazy loading
+$userId = $post->user->fetch()->id;
+
+// $post->tag contains Tag object because of eager loading
+$tagName = $post->tag->name;
+```
+
 ## License:
 
 The MIT License (MIT). Please see [`LICENSE`](./LICENSE) for more information.