DOC: Serialization recommendation is deprecated
#### Location of the documentation

https://pandas.pydata.org/pandas-docs/dev/user_guide/io.html#io-msgpack

#### Documentation problem

Since the deprecation of msgpack for on-the-wire transmission, it is recommended to use pyarrow serialization/deserialization.  However, since pyarrow 2.0, this [has been deprecated](https://arrow.apache.org/docs/python/ipc.html#arbitrary-object-serialization) for arbitrary objects.  A deprecation message is emitted when using the documented code snippet.

```
$ python
Python 3.8.5 (default, Jul 28 2020, 12:59:40) 
[GCC 9.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import pyarrow as pa
>>> pa.__version__
'3.0.0'
>>> pa.default_serialization_context()
<stdin>:1: DeprecationWarning: 'pyarrow.default_serialization_context' is deprecated as of 2.0.0 and will be removed in a future version. Use pickle or the pyarrow IPC functionality instead.
<pyarrow.lib.SerializationContext object at 0x7f23dfa36940>
>>> 
```

#### Suggested fix for documentation

Would pickle be next in line for a recommended on-the-wire format?