[docs] [issue25523] Correct "a" article to "an" article

[Martin Panter]

Changes by Martin Panter <vadmium+py at gmail.com>:


----------
resolution:  -> fixed
stage: commit review -> resolved
status: open -> closed

_______________________________________
Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue25523>
_______________________________________