You need to tell RuboCop to load the Vendor extension. There are three ways to do this:
RuboCop configuration file
Put this into your .rubocop.yml
.
require: rubocop-vendor
Now you can run rubocop
and it will automatically load the RuboCop Vendor
cops together with the standard cops.
Command line
rubocop --require rubocop-vendor
Rake task
RuboCop::RakeTask.new do |task|
task.requires << 'rubocop-vendor'
end