DOC: Removed line about %S parses all the way up to nanosecond even …

…if no (pandas-dev#49349)

* Removed line about %S parses all the way up to nanosecond even if no decimal place present from docstring

* Deleted example code and changed documentation to though note that %f will parse all the way up to nanoseconds

* Fixed CI error

* Changed  to %f

* Removed line between format and exact

* removed whitespace at end of line

* Re-added formatting to %f

pandas/core/tools/datetimes.py

@@ -782,15 +782,7 @@ def to_datetime(
         `strftime documentation
         <https://docs.python.org/3/library/datetime.html
         #strftime-and-strptime-behavior>`_ for more information on choices, though
-        note the following differences:
-
-        - :const:`"%f"` will parse all the way
-          up to nanoseconds;
-
-        - :const:`"%S"` without :const:`"%f"` will capture all the way
-          up to nanoseconds if present as decimal places, and will also handle
-          the case where the number of seconds is an integer.
-
+        note that :const:`"%f"` will parse all the way up to nanoseconds.
     exact : bool, default True
         Control how `format` is used:
 
@@ -969,13 +961,6 @@ def to_datetime(
     ...                format='%Y-%m-%d %H:%M:%S.%f')
     Timestamp('2018-10-26 12:00:00.000000001')
 
-    :const:`"%S"` without :const:`"%f"` will capture all the way
-    up to nanoseconds if present as decimal places.
-
-    >>> pd.to_datetime('2017-03-22 15:16:45.433502912',
-    ...                format='%Y-%m-%d %H:%M:%S')
-    Timestamp('2017-03-22 15:16:45.433502912')
-
     **Non-convertible date/times**
 
     If a date does not meet the `timestamp limitations