[backport to 2.7] Change documentation's `Show Source` link to GitHub (#44)

* Support "bpo-" in Misc/NEWS (#1)
Change the url to 2.7

(cherry picked from commit 79ab8be05fb4ffb5c258d2ca49be5fc2d4880431)

* pyspecific.py: remove space after` bpo-`
1 file changed