Enable Rubocop RSpec/MultipleDescribes (#23672)

.rubocop_todo.yml

@@ -1309,11 +1309,6 @@ RSpec/MissingExampleGroupArgument:
     - 'spec/services/notify_service_spec.rb'
     - 'spec/services/process_mentions_service_spec.rb'
 
-# Offense count: 1
-RSpec/MultipleDescribes:
-  Exclude:
-    - 'spec/routing/well_known_routes_spec.rb'
-
 # Offense count: 599
 RSpec/MultipleExpectations:
   Max: 19

spec/routing/well_known_routes_spec.rb

 require 'rails_helper'
 
-describe 'the host-meta route' do
-  it 'routes to correct place with xml format' do
-    expect(get('/.well-known/host-meta'))
-      .to route_to('well_known/host_meta#show', format: 'xml')
+describe 'Well Known routes' do
+  describe 'the host-meta route' do
+    it 'routes to correct place with xml format' do
+      expect(get('/.well-known/host-meta'))
+        .to route_to('well_known/host_meta#show', format: 'xml')
+    end
   end
-end
 
-describe 'the webfinger route' do
-  it 'routes to correct place with json format' do
-    expect(get('/.well-known/webfinger'))
-      .to route_to('well_known/webfinger#show')
+  describe 'the webfinger route' do
+    it 'routes to correct place with json format' do
+      expect(get('/.well-known/webfinger'))
+        .to route_to('well_known/webfinger#show')
+    end
   end
 end