Add rubocop alias config file

[toydestroyer]

Problem

As previously discussed in issue #138, rubocop-rspec flags a violation of RSpec/EmptyExampleGroup when using rswag-only syntax without it, specify, etc.

Solution

Since the original issue was opened and closed in 2018, rubocop-rspec has released version 2.0, which now supports syntax extension in third-party gems. Details: https://docs.rubocop.org/rubocop-rspec/third_party_rspec_syntax_extensions.html

To resolve this issue, rswag-specs should come with the rubocop rspec alias config. And the README should contain instructions for users on how to enable it.

inherit_gem:
  rswag-specs: .rubocop_rspec_alias_config.yml

Examples:

• Add RuboCop RSpec support test-prof/test-prof#199
• Add RuboCop RSpec support palkan/action_policy#138

Related Issues

#138

Checklist

• Added tests
• Changelog updated
• Added documentation to README.md

Steps to Test or Reproduce

The problem can be reproduced by running rubocop-rspec against the code example from the README:

# spec/requests/blogs_spec.rb
require 'swagger_helper'

describe 'Blogs API' do

  path '/blogs' do

    post 'Creates a blog' do
      tags 'Blogs'
      consumes 'application/json'
      parameter name: :blog, in: :body, schema: {
        type: :object,
        properties: {
          title: { type: :string },
          content: { type: :string }
        },
        required: [ 'title', 'content' ]
      }

      response '201', 'blog created' do
        let(:blog) { { title: 'foo', content: 'bar' } }
        run_test!
      end

      response '422', 'invalid request' do
        let(:blog) { { title: 'foo' } }
        run_test!
      end
    end
  end

[romanblanco]

LGTM 👍

Thank you for the PR, @toydestroyer!