### What changes were proposed in this pull request?
This PR proposes to restructure API files according to the layout, see https://github.com/apache/spark/pull/32799. Now the pandas APIs on Spark are under a separate directory which is same level as other modules such as Spark SQL.
```bash
tree reference
```
**Before:**
```
reference
├── index.rst
├── ps_extensions.rst
├── ps_frame.rst
├── ps_general_functions.rst
├── ps_groupby.rst
├── ps_indexing.rst
├── ps_io.rst
├── ps_ml.rst
├── ps_series.rst
├── ps_window.rst
├── pyspark.ml.rst
├── pyspark.mllib.rst
├── pyspark.pandas.rst
├── pyspark.resource.rst
├── pyspark.rst
├── pyspark.sql.rst
├── pyspark.ss.rst
└── pyspark.streaming.rst
```
**After:**
```
reference
├── index.rst
├── pyspark.ml.rst
├── pyspark.mllib.rst
├── pyspark.pandas
│ ├── extensions.rst
│ ├── frame.rst
│ ├── general_functions.rst
│ ├── groupby.rst
│ ├── index.rst
│ ├── indexing.rst
│ ├── io.rst
│ ├── ml.rst
│ ├── series.rst
│ └── window.rst
├── pyspark.resource.rst
├── pyspark.rst
├── pyspark.sql.rst
├── pyspark.ss.rst
└── pyspark.streaming.rst
```
### Why are the changes needed?
To make the directory structure easier to follow.
### Does this PR introduce _any_ user-facing change?
No.
### How was this patch tested?
Manually built and tested the docs.
Closes#32812 from HyukjinKwon/SPARK-35646-followup.
Authored-by: Hyukjin Kwon <gurwls223@apache.org>
Signed-off-by: Hyukjin Kwon <gurwls223@apache.org>
### What changes were proposed in this pull request?
This PR proposes to port Koalas documentation to PySpark documentation as its initial step.
It ports almost as is except these differences:
- Renamed import from `databricks.koalas` to `pyspark.pandas`.
- Renamed `to_koalas` -> `to_pandas_on_spark`
- Renamed `(Series|DataFrame).koalas` -> `(Series|DataFrame).pandas_on_spark`
- Added a `ps_` prefix in the RST file names of Koalas documentation
Other then that,
- Excluded `python/docs/build/html` in linter
- Fixed GA dependency installataion
### Why are the changes needed?
To document pandas APIs on Spark.
### Does this PR introduce _any_ user-facing change?
Yes, it adds new documentations.
### How was this patch tested?
Manually built the docs and checked the output.
Closes#32726 from HyukjinKwon/SPARK-35587.
Authored-by: Hyukjin Kwon <gurwls223@apache.org>
Signed-off-by: Hyukjin Kwon <gurwls223@apache.org>