Remove specific guidance about avoiding 'CPU'

Author: hugovk

documentation/style-guide.rst

@@ -78,14 +78,6 @@ C API
   Python's `API <https://docs.python.org/3/c-api/>`_ used by C programmers
   to write extension modules. All caps and unhyphenated.
 
-CPU
-   For "central processing unit." Many style guides say this should be
-   spelled out on the first use (and if you must use it, do so!). For
-   the Python documentation, this abbreviation should be avoided since
-   there's no reasonable way to predict which occurrence will be the
-   first seen by the reader. It is better to use the word "processor"
-   instead.
-
 POSIX
    The name assigned to a particular group of standards. This is always
    uppercase.