Add description to rake tasks

Also add a simple "list" task, just to be able to easily check what will
happen with the other two tasks using that list.

Rakefile

@@ -1,12 +1,19 @@
+# frozen_string_literal: true
+
+require 'bundler/setup'
+require 'support/projects'
+require 'mustermann/version'
+
+desc 'Run rspec'
 task(:rspec)     { ruby '-S rspec'      }
+
+desc 'Run "yard stats"'
 task(:doc_stats) { ruby '-S yard stats' }
+
 task default: [:rspec, :doc_stats]
 
+desc 'Build the gems'
 task :pkg do
-  require 'bundler/setup'
-  require 'support/projects'
-  require 'mustermann/version'
-
   rm_rf 'pkg'
   mkdir 'pkg'
 
@@ -18,10 +25,19 @@ task :pkg do
   end
 end
 
+desc 'Push the gems'
 task release: :pkg do
   cd 'pkg' do
     Support::Projects.each do |project|
       ruby "-S gem push #{project}-#{Mustermann::VERSION}.gem"
     end
   end
 end
+
+desc 'List projects'
+task :list do
+  puts "Listing mustermann project..."
+  Support::Projects.each do |project|
+    puts "#{project} VERSION: #{Mustermann::VERSION}"
+  end
+end