Translate 7.8.1 "Subtree Merging": fix errors according with review.
Translate 7.8.1 "Subtree Merging": fix errors according with review (change 'поддерево' on 'субдерево', 'подкаталог' – on 'субдиректория', 'подмодуль' – on 'субмодуль').