MOSCOW DAYS: LIBERATED BY HAROLD ROBBINS
LEAD: ''Russians love to read.'' Try to find a book or an article on the Soviet Union that does not contain these words. The sentiment is usually supported by circulation figures to prove that Soviet readers devour books without being prodded by expensive ad campaigns. But who needs statistics? From Minsk to Yakutsk, no living room is complete without a massive bookcase bursting with ''Complete Works.