Fix RSpec/MissingExampleGroupArgument cop (#25310)

spec/models/email_domain_block_spec.rb

@@ -9,7 +9,7 @@ RSpec.describe EmailDomainBlock do
     context 'when given an e-mail address' do
       let(:input) { "foo@#{domain}" }
 
-      context do
+      context 'with a top level domain' do
         let(:domain) { 'example.com' }
 
         it 'returns true if the domain is blocked' do
@@ -23,7 +23,7 @@ RSpec.describe EmailDomainBlock do
         end
       end
 
-      context do
+      context 'with a subdomain' do
         let(:domain) { 'mail.example.com' }
 
         it 'returns true if it is a subdomain of a blocked domain' do