Add RSpec/ExcessiveDocstringSpacing rubocop rule

This rule was added in rubocop-rspec 2.5.0.

spec/controllers/users/confirmations_controller_spec.rb

@@ -10,7 +10,7 @@ describe Users::ConfirmationsController do
       expect { get :show, params: { token: "non_existent" } }.to raise_error ActiveRecord::RecordNotFound
     end
 
-    it "returns a 422 code with a existent and used token " do
+    it "returns a 422 code with a existent and used token" do
       user = create(:user, confirmation_token: "token1")
 
       get :show, params: { user: user, confirmation_token: "token1" }
@@ -18,7 +18,7 @@ describe Users::ConfirmationsController do
       expect(response).to have_http_status(:unprocessable_entity)
     end
 
-    it "redirect to sign_in page with a existent and not used token " do
+    it "redirect to sign_in page with a existent and not used token" do
       user = create(:user, confirmation_token: "token1", confirmed_at: "")
 
       get :show, params: { user: user, confirmation_token: "token1" }