Remove doc for deprecated function one_hot_encoding (#10367)

This PR removes doc item for deprecated function `one_hot_encoding`.

Authors:
  - Michael Wang (https://github.com/isVoid)

Approvers:
  - Bradley Dice (https://github.com/bdice)
  - Vyas Ramasubramani (https://github.com/vyasr)

URL: #10367

docs/cudf/source/api_docs/dataframe.rst

@@ -209,8 +209,8 @@ Reshaping, sorting, transposing
    DataFrame.T
    DataFrame.transpose
 
-Combining / comparing / joining / merging / encoding
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Combining / comparing / joining / merging
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 .. autosummary::
    :toctree: api/
 
@@ -219,7 +219,6 @@ Combining / comparing / joining / merging / encoding
    DataFrame.join
    DataFrame.merge
    DataFrame.update
-   DataFrame.one_hot_encoding
 
 Numerical operations
 ~~~~~~~~~~~~~~~~~~~~

docs/cudf/source/api_docs/series.rst

@@ -207,14 +207,13 @@ Reshaping, sorting
    Series.repeat
    Series.transpose
 
-Combining / comparing / joining / merging / encoding
-----------------------------------------------------
+Combining / comparing / joining / merging
+-----------------------------------------
 .. autosummary::
    :toctree: api/
 
    Series.append
    Series.update
-   Series.one_hot_encoding
 
 Numerical operations
 ~~~~~~~~~~~~~~~~~~~~