spec: add URL tag
rpmlint complains that there is no URL tag pointing to the software's
website/documentation.  Since liburing does not have a landing page,
point to the cgit page where all information can be found.
@@ -6,6 +6,7 @@ License: LGPLv2+
Group: System Environment/Libraries
Source: %{name}-%{version}.tar.gz
BuildRoot: %{_tmppath}/%{name}-root
+URL: http://git.kernel.dk/cgit/liburing/
%description
Provides native async IO for the Linux kernel, in a fast and efficient
