refactor: 📝 Use References nomenclature instead of URI

app/types/page.mdx

@@ -1,3 +1,50 @@
+## Reference
+
+```typescript
+type Hostname = string;
+type Id = Entity["id"];
+
+type Reference = `${Hostname}:${Id}` | `${Id}`;
+```
+
+A **reference** is a way to refer to any entity within the Versia network. It is a string composed of the following parts:
+
+- The entity's instance's hostname. Optional if that same instance is the creator of the entity.
+    - Punycode encoding is used for internationalized domain names (IDNs).
+    - Example: `example.com`, `example.com:3000`, `xn--ls8h.xn--ls8h`.
+- A colon (`:`) separator, if the hostname is present.
+- The entity's unique identifier. This is the `id` property of the entity.
+
+<Warning>
+    If the hostname is an IPv6 address, it must be enclosed in square brackets.
+    
+    For example: `[2001:db8::1]:3000`.
+</Warning>
+
+
+### Examples
+
+These two examples are equivalent if the instance is `example.com`:
+
+```jsonc
+{
+    "type": "Follow",
+    "id": "3e7e4750-afd4-4d99-a256-02f0710a0520",
+    "author": "6e0204a2-746c-4972-8602-c4f37fc63bbe", // [!code focus]
+    "created_at": "2021-01-01T00:00:00.000Z",
+    "followee": "test.org:02e1e3b2-cb1f-4e4a-b82e-98866bee5de7"
+}
+```
+
+```jsonc
+{
+    "type": "Follow",
+    "id": "3e7e4750-afd4-4d99-a256-02f0710a0520",
+    "author": "example.com:6e0204a2-746c-4972-8602-c4f37fc63bbe", // [!code focus]
+    "created_at": "2021-01-01T00:00:00.000Z",
+    "followee": "test.org:02e1e3b2-cb1f-4e4a-b82e-98866bee5de7"
+}
+```
 
 ## RFC3339