[ci skip] Don’t explicitly mention EventMachine

Since #23152 eliminated the EventMachine dependency, we don’t need to
explicitly mention EventMachine.

Nevertheless, I'm not 100% sure about saying "the websocket-driver loop"
driver… any suggestions, @matthewd or @pixeltrix ? 😅

[ci skip]

actioncable/README.md

@@ -443,11 +443,10 @@ The Ruby side of things is built on top of [faye-websocket](https://github.com/f
 
 ## Deployment
 
-Action Cable is powered by a combination of EventMachine and threads. The
-framework plumbing needed for connection handling is handled in the
-EventMachine loop, but the actual channel, user-specified, work is handled
-in a normal Ruby thread. This means you can use all your regular Rails models
-with no problem, as long as you haven't committed any thread-safety sins.
+Action Cable is powered by a combination of websockets and threads. All of the
+connection management is handled internally by utilizing Ruby’s native thread
+support, which means you can use all your regular Rails models with no problems
+as long as you haven’t committed any thread-safety sins.
 
 But this also means that Action Cable needs to run in its own server process.
 So you'll have one set of server processes for your normal web work, and another

railties/lib/rails/generators/rails/app/templates/app/channels/application_cable/channel.rb

-# Be sure to restart your server when you modify this file. Action Cable runs in an EventMachine loop that does not support auto reloading.
+# Be sure to restart your server when you modify this file. Action Cable runs in a loop that does not support auto reloading.
 module ApplicationCable
   class Channel < ActionCable::Channel::Base
   end

railties/lib/rails/generators/rails/app/templates/app/channels/application_cable/connection.rb

-# Be sure to restart your server when you modify this file. Action Cable runs in an EventMachine loop that does not support auto reloading.
+# Be sure to restart your server when you modify this file. Action Cable runs in a loop that does not support auto reloading.
 module ApplicationCable
   class Connection < ActionCable::Connection::Base
   end