fix one-sentence summary in docstring for `site_config_dir`

[NickleDave]

very minor thing (probably why no-one has noticed it) but the one-sentence summary for site_config_dir is wrong, guessing because someone copied the docstring from site_data_dir (not that I have ever been guilty of this 😇 )

appdirs/appdirs.py

Line 210 in 8eacfa3

r"""Return full path to the user-shared data dir for this application.

def site_config_dir(appname=None, appauthor=None, version=None, multipath=False):
    r"""Return full path to the user-shared data dir for this application.

Happy to fix a PR if you want it fixed, probably it should be a one-word change to match user_config_dir

    r"""Return full path to the user-shared config dir for this application.