Remove 2 unnecessary git commands from step 16 of The Typical Workflow in doc/how_to_sprint.rst

[ArrivalR8]

Remove these two unnecessary git commands from step 16 of The Typical Workflow in doc/how_to_sprint.rst:

git pull upstream master
git checkout fix/bug_name

(as stated by Jonathan Rocher as he presented the Sprint Tutorial at SciPy 2018 on 7/14/2018)