DOC: update the pandas.DateTimeArrayMixin.is_month_start docstring

pandas/core/arrays/datetimes.py

@@ -998,48 +998,62 @@ def date(self):
         'dim',
         "The number of days in the month")
     daysinmonth = days_in_month
-    is_month_start = _field_accessor(
-        'is_month_start',
-        'is_month_start',
-        "Logical indicating if first day of month (defined by frequency)")
-    is_month_end = _field_accessor(
-        'is_month_end',
-        'is_month_end',
-        """
-        Indicator for whether the date is the last day of the month.
+    _is_month_doc = """
+        Indicates whether the date is the {first_or_last} day of the month.
 
         Returns
         -------
         Series or array
-            For Series, returns a Series with boolean values. For
-            DatetimeIndex, returns a boolean array.
+            For Series, returns a Series with bool.
+            For DatetimeIndex, returns a bool array.
 
         See Also
         --------
-        is_month_start : Indicator for whether the date is the first day
-            of the month.
+        is_month_{end_or_start} : Return a boolean indicating whether the date
+            is the {last_or_first} day of the month.
 
         Examples
         --------
         This method is available on Series with datetime values under
         the ``.dt`` accessor, and directly on DatetimeIndex.
 
-        >>> dates = pd.Series(pd.date_range("2018-02-27", periods=3))
-        >>> dates
+        >>> s = pd.Series(pd.date_range("2018-02-27", periods=3))
+        >>> s
         0   2018-02-27
         1   2018-02-28
         2   2018-03-01
         dtype: datetime64[ns]
-        >>> dates.dt.is_month_end
-        0    False
-        1    True
-        2    False
+        >>> s.dt.is_month_{start_or_end}
+        0    {FT[0]}
+        1    {FT[1]}
+        2    {FT[2]}
         dtype: bool
 
         >>> idx = pd.date_range("2018-02-27", periods=3)
-        >>> idx.is_month_end
-        array([False,  True, False], dtype=bool)
-        """)
+        >>> idx.is_month_{start_or_end}
+        array([{FT[3]}, {FT[4]}, {FT[5]}])
+    """
+    is_month_start = _field_accessor(
+        'is_month_start',
+        'is_month_start',
+        _is_month_doc.format(
+            first_or_last='first',
+            start_or_end='start',
+            FT=[False, False, True, False, False, True],
+            end_or_start='end',
+            last_or_first='last'
+        ))
+
+    is_month_end = _field_accessor(
+        'is_month_end',
+        'is_month_end',
+        _is_month_doc.format(
+            first_or_last='last',
+            start_or_end='end',
+            FT=[False, True, False, False, True, False],
+            end_or_start='start',
+            last_or_first='first'
+        ))
     is_quarter_start = _field_accessor(
         'is_quarter_start',
         'is_quarter_start',