Improve code documentation for pmpy communication.

app/models/jupiter_core/depositable.rb

@@ -171,7 +171,9 @@ def push_entity_for_preservation
     $queue.with do |connection|
       # pushmi_pullyu requires both the id and type of the depositable
       connection.zadd(queue_name, Time.now.to_f, { uuid: id, type: self.class.table_name }.to_json)
-      # Here we add the attempt pmpy will be trying to ingest the depositable. We start at 0
+      # Add the attempt count as value 0 that pmpy will use to count the tries to ingest the depositable. If the key
+      # already exists, the value will be reset to 0. the ```connection.zadd``` method called before resets the score as
+      # well. These two pieces of information let PMPY know that the entity needs to be deposited ASAP
       connection.set("#{Rails.application.secrets.attempt_ingest_prefix}#{id}", 0)
     end