Fix docs for pattern option so they are more accurate.
Fix docs for pattern option so they are more accurate.

Fixes #2176.
rspec/rspec-core,rspec/rspec-core,azbshiri/rspec-core,azbshiri/rspec-core,xmik/rspec-core,xmik/rspec-core,azbshiri/rspec-core,rspec/rspec-core,xmik/rspec-core