DOC: Remove keep=False docs on nlargest/nsmallest (#18617)

(cherry picked from commit 73ed6de)

Author: AaronCritchley

pandas/core/frame.py

@@ -3751,7 +3751,7 @@ def nlargest(self, n, columns, keep='first'):
             Number of items to retrieve
         columns : list or str
             Column name or names to order by
-        keep : {'first', 'last', False}, default 'first'
+        keep : {'first', 'last'}, default 'first'
             Where there are duplicate values:
             - ``first`` : take the first occurrence.
             - ``last`` : take the last occurrence.
@@ -3788,7 +3788,7 @@ def nsmallest(self, n, columns, keep='first'):
             Number of items to retrieve
         columns : list or str
             Column name or names to order by
-        keep : {'first', 'last', False}, default 'first'
+        keep : {'first', 'last'}, default 'first'
             Where there are duplicate values:
             - ``first`` : take the first occurrence.
             - ``last`` : take the last occurrence.

pandas/core/series.py

@@ -2023,7 +2023,7 @@ def nlargest(self, n=5, keep='first'):
         ----------
         n : int
             Return this many descending sorted values
-        keep : {'first', 'last', False}, default 'first'
+        keep : {'first', 'last'}, default 'first'
             Where there are duplicate values:
             - ``first`` : take the first occurrence.
             - ``last`` : take the last occurrence.
@@ -2070,7 +2070,7 @@ def nsmallest(self, n=5, keep='first'):
         ----------
         n : int
             Return this many ascending sorted values
-        keep : {'first', 'last', False}, default 'first'
+        keep : {'first', 'last'}, default 'first'
             Where there are duplicate values:
             - ``first`` : take the first occurrence.
             - ``last`` : take the last occurrence.