Add example for SizedQueue#num_waiting
Add example for SizedQueue#num_waiting

eregon/rubyspec,nobu/rubyspec,nobu/rubyspec,sgarciac/spec,wied03/rubyspec,ruby/spec,kachick/rubyspec,eregon/rubyspec,nobu/rubyspec,kachick/rubyspec,wied03/rubyspec,ruby/rubyspec,sgarciac/spec,ruby/spec,kachick/rubyspec,ruby/spec,ruby/rubyspec,eregon/rubyspec,sgarciac/spec,wied03/rubyspec