Prepend `$` to example CLI commands [ci-skip]

This allows the syntax highlighter to recognize the code as CLI commands.

actionmailbox/app/controllers/action_mailbox/ingresses/relay/inbound_emails_controller.rb

@@ -41,7 +41,7 @@ module ActionMailbox
   #    If your application lives at <tt>https://example.com</tt>, you would configure the Postfix SMTP server to pipe
   #    inbound emails to the following command:
   #
-  #        bin/rails action_mailbox:ingress:postfix URL=https://example.com/rails/action_mailbox/postfix/inbound_emails INGRESS_PASSWORD=...
+  #        $ bin/rails action_mailbox:ingress:postfix URL=https://example.com/rails/action_mailbox/postfix/inbound_emails INGRESS_PASSWORD=...
   #
   #    Built-in ingress commands are available for these popular SMTP servers:
   #

actionpack/lib/action_dispatch/routing.rb

@@ -238,7 +238,7 @@ module ActionDispatch
   #
   # == View a list of all your routes
   #
-  #   bin/rails routes
+  #   $ bin/rails routes
   #
   # Target a specific controller with <tt>-c</tt>, or grep routes
   # using <tt>-g</tt>. Useful in conjunction with <tt>--expanded</tt>

activerecord/lib/active_record/middleware/database_selector.rb

@@ -24,7 +24,7 @@ module ActiveRecord
     # To use the DatabaseSelector in your application with default settings,
     # run the provided generator.
     #
-    #   bin/rails g active_record:multi_db
+    #   $ bin/rails g active_record:multi_db
     #
     # This will create a file named +config/initializers/multi_db.rb+ with the
     # following contents:

activerecord/lib/active_record/migration.rb

@@ -371,7 +371,8 @@ module ActiveRecord
   # The \Rails package has several tools to help create and apply migrations.
   #
   # To generate a new migration, you can use
-  #   bin/rails generate migration MyNewMigration
+  #
+  #   $ bin/rails generate migration MyNewMigration
   #
   # where MyNewMigration is the name of your migration. The generator will
   # create an empty migration file <tt>timestamp_my_new_migration.rb</tt>
@@ -380,7 +381,7 @@ module ActiveRecord
   #
   # There is a special syntactic shortcut to generate migrations that add fields to a table.
   #
-  #   bin/rails generate migration add_fieldname_to_tablename fieldname:string
+  #   $ bin/rails generate migration add_fieldname_to_tablename fieldname:string
   #
   # This will generate the file <tt>timestamp_add_fieldname_to_tablename.rb</tt>, which will look like this:
   #   class AddFieldnameToTablename < ActiveRecord::Migration[7.2]

railties/lib/rails/engine.rb

@@ -328,7 +328,7 @@ module Rails
   # To use engine's migrations in application you can use the rake task below, which copies them to
   # application's dir:
   #
-  #   rake ENGINE_NAME:install:migrations
+  #   $ rake ENGINE_NAME:install:migrations
   #
   # Note that some of the migrations may be skipped if a migration with the same name already exists
   # in application. In such a situation you must decide whether to leave that migration or rename the

railties/lib/rails/generators/base.rb

@@ -79,7 +79,7 @@ module Rails
       #
       # For example, if the user invoke the controller generator as:
       #
-      #   bin/rails generate controller Account --test-framework=test_unit
+      #   $ bin/rails generate controller Account --test-framework=test_unit
       #
       # The controller generator will then try to invoke the following generators:
       #
@@ -134,11 +134,11 @@ module Rails
       # All hooks come with switches for user interface. If you do not want
       # to use any test framework, you can do:
       #
-      #   bin/rails generate controller Account --skip-test-framework
+      #   $ bin/rails generate controller Account --skip-test-framework
       #
       # Or similarly:
       #
-      #   bin/rails generate controller Account --no-test-framework
+      #   $ bin/rails generate controller Account --no-test-framework
       #
       # ==== Boolean hooks
       #
@@ -150,7 +150,7 @@ module Rails
       #
       # Then, if you want webrat to be invoked, just supply:
       #
-      #   bin/rails generate controller Account --webrat
+      #   $ bin/rails generate controller Account --webrat
       #
       # The hooks lookup is similar as above:
       #