fix doctest

Author: fchapoton

src/sage/categories/morphism.pyx

@@ -178,7 +178,8 @@ cdef class Morphism(Map):
             sage: f = R.hom([t**2])
             sage: f.category()
             Category of endsets of unital magmas and right modules over
-             (euclidean domains and infinite enumerated sets and metric spaces)
+             (Dedekind domains and euclidean domains
+              and infinite enumerated sets and metric spaces)
              and left modules over (Dedekind domains and euclidean domains
              and infinite enumerated sets and metric spaces)