DOC: update the pandas.Series.dt.total_seconds docstring

[ijmbarr]

Checklist for the pandas documentation sprint (ignore this if you are doing
an unrelated PR):

• PR title is "DOC: update the docstring"
• The validation script passes: scripts/validate_docstrings.py <your-function-or-method>
• The PEP8 style check passes: git diff upstream/master -u -- "*.py" | flake8 --diff
• The html version looks good: python doc/make.py --single <your-function-or-method>
• It has been proofread on language by another sprint participant

Please include the output of the validation script below between the "```" ticks:

################################################################################
################## Docstring (pandas.Series.dt.total_seconds) ##################
################################################################################

Return total duration of each element expressed in seconds.

Return a series with the same length and index as the original,
containing the length of each element expressed in seconds.

Returns
-------
s : pandas.Series
    a series of type `float64`.

Examples
--------
>>> s = pd.Series(pd.to_timedelta(np.arange(5), unit='d'))
>>> s
0   0 days
1   1 days
2   2 days
3   3 days
4   4 days
dtype: timedelta64[ns]
>>> s.dt.total_seconds()
0         0.0
1     86400.0
2    172800.0
3    259200.0
4    345600.0
dtype: float64

################################################################################
################################## Validation ##################################
################################################################################

Errors found:
        Errors in parameters section
                Parameters {'args', 'kwargs'} not documented
        See Also section not found

If the validation script still gives errors, but you think there is a good reason
to deviate in this case (and there are certainly such cases), please state this
explicitly.

Checklist for other PRs (remove this part if you are doing a PR for the pandas documentation sprint):

• closes #xxxx
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• whatsnew entry

[mabelvj]

See Alsosection is missing. Maybe it could be useful to reference datetime documentation.

[ijmbarr]

Added.

[jorisvandenbossche]

Looks good to me! (added minor comment)

@TomAugspurger we have again the problem of index vs .dt accessor. Did we already have a solution for this? (the current PR now documents it like .dt)

[jorisvandenbossche]

"a series" -> "Series"

[codecov]

Codecov Report

Merging #20159 into master will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master   #20159      +/-   ##
==========================================
- Coverage   91.72%    91.7%   -0.03%     
==========================================
  Files         150      150              
  Lines       49156    49165       +9     
==========================================
- Hits        45090    45087       -3     
- Misses       4066     4078      +12

Flag	Coverage Δ
#multiple	90.09% <ø> (-0.03%)	⬇️
#single	41.86% <ø> (+0.01%)	⬆️

Impacted Files	Coverage Δ
pandas/core/indexes/timedeltas.py	91.03% <ø> (ø)	⬆️
pandas/plotting/_converter.py	65.07% <0%> (-1.74%)	⬇️
pandas/core/series.py	93.84% <0%> (-0.02%)	⬇️
pandas/core/base.py	96.78% <0%> (-0.02%)	⬇️
pandas/core/indexes/base.py	96.66% <0%> (-0.01%)	⬇️
pandas/core/strings.py	98.32% <0%> (ø)	⬆️
pandas/core/indexing.py	93.02% <0%> (ø)	⬆️
pandas/core/groupby.py	92.14% <0%> (ø)	⬆️
pandas/plotting/_misc.py	38.98% <0%> (ø)	⬆️
pandas/core/indexes/multi.py	95.06% <0%> (ø)	⬆️
... and 8 more

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[TomAugspurger]

Made this generic for TimedeltaIndex and Series[timedelta64].

[jorisvandenbossche]

Yes, that looks like a good solution