Fix solution for exercise 5

[jsyzlbw]

Fixes #185.

The solution for exercise 5 currently uses %run with a shell command:

%run `python -c "import numpy; numpy.info(numpy.add)"`

In IPython/Jupyter, %run expects a Python file/script, so this can fail with File 'python.py' not found.
Since the exercise asks for a command-line solution, this PR changes it to:

python -c "import numpy; numpy.info(numpy.add)"

[rougier]

Thanks for the fix. Can you apply on kth files instead (they are used to generate others)

[jsyzlbw]

Applied the fix to source/exercises100.ktx and regenerated the Markdown files.
Thank you very much for review

[rougier]

Thanks. Just the kth file please, I'll regenerate other files.

[jsyzlbw]

OK👌