Update Documentation: Add details about how to vary queue priority (#494)

* Add details about how to vary queue priority

* Update README.md

---------

Co-authored-by: Chris Oliver <[email protected]>

Author: phil-6

README.md

@@ -374,9 +374,29 @@ Each of these options are available for every delivery method (individual or bul
 
 * `config.if` — Intended for a lambda or method; runs after the `wait` if configured; cancels the delivery method if returns falsey
 * `config.unless`  — Intended for a lambda or method; runs after the `wait` if configured; cancels the delivery method if returns truthy
+
+The following are evaluated in the context of the Notification so it can be customize to the recipient:
+
 * `config.wait` — (Should yield an `ActiveSupport::Duration`) Delays the job that runs this delivery method for the given duration of time
 * `config.wait_until` — (Should yield a specific time object) Delays the job that runs this delivery method until the specific time specified
-* `config.queue` — Sets the ActiveJob queue name to be used for the job that runs this delivery method
+* `config.queue` — Sets the ActiveJob queue name to be used for the job that runs this delivery method.
+
+When using a symbol, the matching method must be defined inside the `notification_methods` block:
+
+```ruby
+# app/notifiers/message_notifier.rb
+class MessageNotifier < Noticed::Event
+  deliver_by :delivery_method do |config|
+    config.queue = :queue
+  end
+
+  notification_methods do
+    def queue
+      "high_priority"
+    end
+  end
+end
+```
 
 ### 📨 Sending Notifications