notion of special tokens <s>, <sep> and </s>

README.md

@@ -37,6 +37,16 @@ license: cc-by-nc-4.0
 2) дисконтируем результаты п.1 символьной близостью (3-граммы) по коэффициенту Жаккара. Это штрафует перестановочные
 перефразировки, воспроизведение исходного текста и небольшие переписывания.
 
+### Формат входных данных
+
+На вход модели подается исходный текст с добавлением токенов ```<s>``` в начале и ```<sep>``` в конце, например:
+
+```
+input_text = '<s>Мороз и солнце, день чудесный<sep>'
+```
+
+Результат генерации будет содержать текст с токеном ```</s>``` - это конец последовательности.
+
 ### Пример использования
 
 Следующий код позволяет ввести в консоли короткое предложение