[docs] Replace string with bytes in doc of unicode-escape an raw-unicode-escape (issue 28750)

[barry at dadadata.net]

Small wording nit


http://bugs.python.org/review/28750/diff/19218/Doc/c-api/unicode.rst
File Doc/c-api/unicode.rst (left):

http://bugs.python.org/review/28750/diff/19218/Doc/c-api/unicode.rst#oldcode1299
Doc/c-api/unicode.rst:1299: Encode a Unicode object using Unicode-Escape
and return the result as Python
s/as Python/as a Python/

http://bugs.python.org/review/28750/diff/19218/Doc/c-api/unicode.rst#oldcode1330
Doc/c-api/unicode.rst:1330: Encode a Unicode object using
Raw-Unicode-Escape and return the result as
Same here.

http://bugs.python.org/review/28750/