[SSSD] [PATCH] Rename sssd.conf to sssd-example.conf

[Stephen Gallagher]

This file should not be installed by default. It leads to user
confusion. We will instead install it as documentation. Authconfig or
the SSSDConfig API can generate a file trivially.

Also fixes the incorrect example of entry_cache_nowait_percentage

https://bugzilla.redhat.com/show_bug.cgi?id=697893