DOC: fix cross-reference to period_array in PeriodArray

Author: plammens

pandas/core/arrays/period.py

@@ -70,7 +70,7 @@ class PeriodArray(PeriodMixin, dtl.DatetimeLikeArrayMixin, dtl.DatelikeOps):
     """
     Pandas ExtensionArray for storing Period data.
 
-    Users should use :func:`period_array` to create new instances.
+    Users should use :func:`~pandas.period_array` to create new instances.
 
     Parameters
     ----------