Add example for Series.str.slice() (#27832)

* Add example for Series.str.slice()

Author: avelineg

pandas/core/strings.py

@@ -1442,6 +1442,12 @@ def str_slice(arr, start=None, stop=None, step=None):
     2    hameleon
     dtype: object
 
+    >>> s.str.slice(start=-1)
+    0           a
+    1           x
+    2           n
+    dtype: object
+
     >>> s.str.slice(stop=2)
     0    ko
     1    fo