Apply suggestions from code review

Co-authored-by: cheuberg <[email protected]>

Author: dkrenn

src/sage/combinat/k_regular_sequence.py

@@ -1044,7 +1044,7 @@ def one(self):
             sage: O.linear_representation()
             ((1), Finite family {0: [1], 1: [0]}, (1))
 
-        TESTS:
+        TESTS::
 
             sage: Seq2.one() is Seq2.one()
             True

src/sage/combinat/recognizable_series.py

@@ -1968,7 +1968,7 @@ def one(self):
             sage: O.linear_representation()
             ((1), Finite family {0: [0], 1: [0]}, (1))
 
-        TESTS:
+        TESTS::
 
             sage: Rec.one() is Rec.one()
             True