DOC: fix SyntaxError in doc build on Windows
i'm getting this error for most files during doc build on Windows...

```
>>>-------------------------------------------------------------------------
Exception in C:\Users\simon\OneDrive\code\pandas-simonjayhawkins\doc\source\development\contributing.rst at block ending on line None
Specify :okexcept: as an option in the ipython:: block to suppress this message
  File "<ipython-input-1-9cb881b1c9b0>", line 1
    os.chdir('C:\Users\simon\OneDrive\code\pandas-simonjayhawkins\doc')
            ^
SyntaxError: (unicode error) 'unicodeescape' codec can't decode bytes in position 2-3: truncated \UXXXXXXXX escape

<<<-------------------------------------------------------------------------
```