One-Pan Pasta with Chicken Sausage, Mushrooms, and Collards

Heat oil in a large, high-sided skillet over medium-high. Add sausage and mushrooms; cook, stirring often, until browned, about 8 minutes. Add stock and next 5 ingredients; bring to a boil. Cook, stirring constantly, until pasta is al dente and liquid is mostly absorbed, about 15 minutes. Stir in vinegar, and sprinkle with crushed red pepper.