docs add more docs to app/{jobs,logical}.

These were missed in the last commit.

app/logical/concerns/mentionable.rb

@@ -1,3 +1,6 @@
+# A concern that handles @mentions in comments and forum posts. Sends a DMail
+# to mentioned users when a comment or forum post is created or edited to add
+# new mentions.
 module Mentionable
   extend ActiveSupport::Concern
 

app/logical/danbooru/http/redirector.rb

@@ -1,6 +1,6 @@
 # A HTTP::Feature that automatically follows HTTP redirects.
-# https://developer.mozilla.org/en-US/docs/Web/HTTP/Redirections
-
+#
+# @see https://developer.mozilla.org/en-US/docs/Web/HTTP/Redirections
 module Danbooru
   class Http
     class Redirector < HTTP::Feature

app/logical/storage_manager/local.rb

@@ -1,3 +1,4 @@
+# A StorageManager that stores files on the local filesystem.
 class StorageManager::Local < StorageManager
   DEFAULT_PERMISSIONS = 0o644
 

app/logical/storage_manager/null.rb

@@ -1,3 +1,5 @@
+# A null StorageManager that doesn't store files at all. Used for testing or
+# disabling backups.
 class StorageManager::Null < StorageManager
   def initialize(base_url: "/", base_dir: "/")
     super