Remove obsolete Group tag

References: https://fedoraproject.org/wiki/Changes/Remove_Group_Tag

rubygem-builder.spec

@@ -4,7 +4,6 @@ Name: rubygem-%{gem_name}
 Version: 3.2.3
 Release: 5%{?dist}
 Summary: Builders for MarkUp
-Group: Development/Languages
 License: MIT
 URL: http://onestepback.org
 Source0: https://rubygems.org/gems/%{gem_name}-%{version}.gem
@@ -31,7 +30,6 @@ data simple to do. Currently the following builder objects are supported:
 
 %package doc
 Summary: Documentation for %{name}
-Group: Documentation
 Requires: %{name} = %{version}-%{release}
 BuildArch: noarch