apacheGH-44711: [Docs][Python] Add missing canonical extension types …

…to PyArrow arrays and datatypes docs (apache#44880)

Some of the canonical extension types which are implemented in PyArrow
missing from the PyArrow arrays and datatypes docs pages have been added
like JSON, UUID, Decimal256 and Bool8.
* GitHub Issue: apache#44711

docs/source/python/api/arrays.rst

@@ -73,6 +73,7 @@ may expose data type-specific methods or properties.
    DurationArray
    MonthDayNanoIntervalArray
    Decimal128Array
+   Decimal256Array
    DictionaryArray
    ListArray
    FixedSizeListArray
@@ -86,6 +87,9 @@ may expose data type-specific methods or properties.
    ExtensionArray
    FixedShapeTensorArray
    OpaqueArray
+   JsonArray
+   UuidArray
+   Bool8Array
 
 .. _api.scalar:
 
@@ -112,6 +116,7 @@ classes may expose data type-specific methods or properties.
    Int16Scalar
    Int32Scalar
    Int64Scalar
+   NullScalar
    UInt8Scalar
    UInt16Scalar
    UInt32Scalar
@@ -134,9 +139,11 @@ classes may expose data type-specific methods or properties.
    DurationScalar
    MonthDayNanoIntervalScalar
    Decimal128Scalar
+   Decimal256Scalar
    DictionaryScalar
    RunEndEncodedScalar
    ListScalar
+   FixedSizeListScalar
    LargeListScalar
    ListViewScalar
    LargeListViewScalar
@@ -146,3 +153,6 @@ classes may expose data type-specific methods or properties.
    ExtensionScalar
    FixedShapeTensorScalar
    OpaqueScalar
+   JsonScalar
+   UuidScalar
+   Bool8Scalar

docs/source/python/api/datatypes.rst

@@ -68,7 +68,13 @@ These should be used to create Arrow data types and schemas.
    dictionary
    run_end_encoded
    fixed_shape_tensor
+   union
+   dense_union
+   sparse_union
    opaque
+   bool8
+   uuid
+   json_
    field
    schema
    from_numpy_dtype
@@ -96,13 +102,19 @@ functions above.
    DataType
    DictionaryType
    ListType
+   ListViewType
+   FixedSizeListType
    LargeListType
+   LargeListViewType
    MapType
    StructType
    UnionType
+   DenseUnionType
+   SparseUnionType
    TimestampType
    Time32Type
    Time64Type
+   DurationType
    FixedSizeBinaryType
    Decimal128Type
    Decimal256Type
@@ -115,8 +127,10 @@ Specific classes and functions for extension types.
 .. autosummary::
    :toctree: ../generated/
 
+   BaseExtensionType
    ExtensionType
    PyExtensionType
+   UnknownExtensionType
    register_extension_type
    unregister_extension_type
 
@@ -128,6 +142,9 @@ implemented by PyArrow.
 
    FixedShapeTensorType
    OpaqueType
+   JsonType
+   UuidType
+   Bool8Type
 
 .. _api.types.checking:
 .. currentmodule:: pyarrow.types