chore: update plurals at i18n plugin

docs/plugins/official/i18n.md

@@ -94,6 +94,20 @@ const bot = new Bot(process.env.BOT_TOKEN as string)
     });
 ```
 
+### Plurals
+
+```ts
+import { pluralizeEnglish, pluralizeRussian } from "@gramio/i18n";
+
+const count = 5;
+
+console.log(`You have ${count} ${pluralizeEnglish(count, "apple", "apples")}.`); // You have 5 apples.
+
+console.log(
+    `У вас ${count} ${pluralizeRussian(count, "яблоко", "яблока", "яблок")}.`
+); // У вас 5 яблок.
+```
+
 `ExtractLanguages` helps you extract languages types from i18n instance.
 
 ```ts