improve docstring

Author: charlesdong1991

pandas/core/reshape/merge.py

@@ -159,11 +159,13 @@ def merge_ordered(left, right, on=None,
         left DataFrame
     fill_method : {'ffill', None}, default None
         Interpolation method for data
-    suffixes : 2-length sequence (tuple, list, ...)
-        Suffix to apply to overlapping column names in the left and right
-        side, respectively. And each element should be either a str or None,
-        and at least one of elements must not be str. Valid inputs are like:
-        (str, str), [str, str], (None, str), [str, None], [None, str] etc
+    suffixes : Sequence
+        A length-2 sequence where each element is optionally a string
+        indicating the suffix to add to overlapping column names in
+        `left` and `right` respectively. Pass a value of `None` instead
+        of a string to indicate that the column name from `left` or
+        `right` should be left as-is, with no suffix. At least one of the
+        values must not be None.
     how : {'left', 'right', 'outer', 'inner'}, default 'outer'
         * left: use only keys from left frame (SQL: left outer join)
         * right: use only keys from right frame (SQL: right outer join)