Fix Package Name typo in pip install instructions (#609)
Fix Package Name typo in pip install instructions (#609)

Change package name in pip install instructions to match pypi with - instead of _

Signed-off-by: Norman Gehrsitz <a14f031d011096e663bdf7c923e1b875ae44edfa@student.dhbw-kahlsruhe.de>
prometheus/client_python