Remove implementation details from apply docstrings

[brandon-b-miller]

Removes some unnecessary implementation detail from apply docstrings and updates them where necessary.

[codecov]

Codecov Report

Merging #10651 (57d5e82) into branch-22.06 (3c13ef1) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@               Coverage Diff                @@
##           branch-22.06   #10651      +/-   ##
================================================
+ Coverage         86.33%   86.37%   +0.03%     
================================================
  Files               140      140              
  Lines             22289    22304      +15     
================================================
+ Hits              19244    19265      +21     
+ Misses             3045     3039       -6     

Impacted Files	Coverage Δ
python/cudf/cudf/core/algorithms.py	90.47% <ø> (ø)
python/cudf/cudf/core/groupby/groupby.py	91.72% <ø> (+0.22%)	⬆️
python/cudf/cudf/core/multiindex.py	92.14% <ø> (ø)
python/cudf/cudf/core/series.py	95.28% <ø> (ø)
python/cudf/cudf/core/single_column_frame.py	96.52% <ø> (+0.07%)	⬆️
python/cudf/cudf/utils/cudautils.py	59.83% <ø> (ø)
python/cudf/cudf/utils/utils.py	90.28% <ø> (ø)
python/cudf/cudf/core/column/lists.py	92.79% <100.00%> (+1.38%)	⬆️
python/cudf/cudf/core/dataframe.py	93.65% <100.00%> (+0.06%)	⬆️
python/cudf/cudf/utils/ioutils.py	79.60% <100.00%> (ø)
... and 10 more

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[shwina]

Thanks, @brandon-b-miller!

@gpucibot merge

[shwina]

@gpucibot merge