linux_distribution() return on CentOS differs from the README

From the README

>>> import distro
>>> distro.linux_distribution(full_distribution_name=False)
('centos', '7.1.1503', 'Core')

Actual behavior

>>> import distro
>>> distro.linux_distribution(full_distribution_name=False)
('centos', '7', 'Core')

The same goes for CentOS 8:

>>> import distro
>>> distro.linux_distribution(full_distribution_name=False)
('centos', '8', 'Core')

Possible solutions

1. Use best=True when getting the version in linux_distribution()
2. Add a best_version argument to linux_distribution() to allow this to be passed through.

I do think that adding a best_version argument would be a good idea. However, I’m not sure defaulting to best=True helps, since it adds the maintenance releases to Ubuntu LTS releases.

So, perhaps this current behavior is best, since it makes the behavior of linux_distribution more congruent with other Linux distros. If that is indeed the position of the project maintainers, and no changes need to be made to the code, I can open a PR to update the README.

[terminalmage]

There should also be changes to the README.md. The example usage of linux_distribution should be corrected to match the actual output. In addition, if the code is being deprecated, the README should state this. And if there is recommended usage, that recommended usage should be in the README. Seems a bit nonsensical to have the documentation show only deprecated usage, IMO.

[jdufresne]

👍 Done in #296.