DOC: Add link description

Also remove errant space

Author: wjandrea

pandas/_libs/tslibs/timedeltas.pyx

@@ -1739,8 +1739,8 @@ cdef class _Timedelta(timedelta):
         """
         Format the Timedelta as ISO 8601 Duration.
 
-        ``P[n]Y[n]M[n]DT[n]H[n]M[n]S``, where the ``[n]`` s are replaced by the
-        values. See https://en.wikipedia.org/wiki/ISO_8601#Durations.
+        ``P[n]Y[n]M[n]DT[n]H[n]M[n]S``, where the ``[n]``s are replaced by the
+        values. See Wikipedia: `ISO 8601 § Durations <https://en.wikipedia.org/wiki/ISO_8601#Durations>`_.
 
         Returns
         -------