docstring fix

Author: Matthias Koeppe

src/sage/geometry/polyhedron/library.py

@@ -933,7 +933,7 @@ def snub_cube(self, exact=False, base_ring=None, backend=None, verbose=False):
 
         INPUT:
 
-        - ``exact`` - (boolean, default ``False``) if ``True`` use exact
+        - ``exact`` -- (boolean, default ``False``) if ``True`` use exact
           coordinates instead of floating point approximations
 
         - ``base_ring`` -- the field to use. If ``None`` (the default), construct