fix RT03 for pandas.Series.str.find

Author: KatsiarynaDzibrova

pandas/core/strings/accessor.py

@@ -2971,6 +2971,9 @@ def extractall(self, pat, flags: int = 0) -> DataFrame:
     Returns
     -------
     Series or Index of int.
+        A Series (if the input is a Series) or an Index (if the input is an
+        Index) of the %(side)s indexes corresponding to the positions where the
+        substring is found in each string of the input.
 
     See Also
     --------
@@ -2980,9 +2983,9 @@ def extractall(self, pat, flags: int = 0) -> DataFrame:
     --------
     For Series.str.find:
 
-    >>> ser = pd.Series(["cow_", "duck_", "do_ve"])
+    >>> ser = pd.Series(["_cow_", "duck_", "do_v_e"])
     >>> ser.str.find("_")
-    0   3
+    0   0
     1   4
     2   2
     dtype: int64