Allow to use short example definition

[artofhuman]

This is an enhancement request.

Proposal:
Allow to use example in two ways

1. Test case without description. Such tests should not be rendered in documentation.

example do
   do_request
   # ...
end

It should allow writing tests cases without noisy document: false. Also, tests wrote with using rspec it should not be passed to documentation without description

it do
  do_request
  #...
end

2. Add :nodoc according document: false.

example "get items", :nodoc do
   do_request
   # ...
end