Add missing APIs to documentation.

[bdice]

This adds a bunch of missing methods to the documentation and removes methods that no longer exist.

When building, Sphinx issues warnings like this one, which indicates that a method isn't documented:

.../cudf/docs/cudf/source/api_docs/api/cudf.Series.pct_change.rst: WARNING: document isn't included in any toctree

and this one, which indicates that a documented method no longer exists:

WARNING: [autosummary] failed to import cudf.Series.ceil.
Possible hints:
* ModuleNotFoundError: No module named 'cudf.Series'
* AttributeError: type object 'Series' has no attribute 'ceil'
* ImportError:

This PR doesn't fix all of the warnings/errors, but it is a good chunk of them.

[galipremsagar]

Are indexing docs gone?

[bdice]

They never existed, as far as I can tell!

I searched through the history from branch-0.14 to branch-22.04 and never found the file indexing.rst. I suspect this was copied from pandas and never checked. It was meant to point to https://github.com/pandas-dev/pandas/blob/main/doc/source/user_guide/indexing.rst. Originally added in PR #8746.

[galipremsagar]

I see, my mistake. Sorry for that, should we also be having a similar page to https://pandas.pydata.org/docs/user_guide/indexing.html#indexing? Not in the scope of this PR but we can track in an open issue.

[bdice]

I don't think we need it. If we do need it, we could have an outbound link to the pandas docs and avoid maintaining such a page.

[codecov]

Codecov Report

Merging #10643 (dd0cae8) into branch-22.06 (3c13ef1) will increase coverage by 0.04%.
The diff coverage is 100.00%.

@@               Coverage Diff                @@
##           branch-22.06   #10643      +/-   ##
================================================
+ Coverage         86.33%   86.37%   +0.04%     
================================================
  Files               140      140              
  Lines             22289    22290       +1     
================================================
+ Hits              19244    19254      +10     
+ Misses             3045     3036       -9     

Impacted Files	Coverage Δ
python/cudf/cudf/core/algorithms.py	90.47% <ø> (ø)
python/cudf/cudf/core/dataframe.py	93.59% <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	96.45% <ø> (ø)
python/cudf/cudf/utils/cudautils.py	59.83% <ø> (ø)
python/cudf/cudf/utils/ioutils.py	79.60% <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%)	⬆️
... and 6 more

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[galipremsagar]

@gpucibot merge