setup.py: added url to repo on github

setup.py

@@ -7,6 +7,7 @@ setuptools.setup(
     use_scm_version=True,
     author='Fabian Peter Hammerle',
     author_email='fabian@hammerle.me',
+    url='https://github.com/fphammerle/acpi-backlight',
     packages=['acpi_backlight'],
     setup_requires=['setuptools_scm'],
     classifiers=[