Add comment regarding configuration options and update changelog.

CHANGELOG.md

@@ -7,6 +7,7 @@ Exclamation symbols (:exclamation:) note something of importance e.g. breaking c
 ### Added
 - Callbacks can be added to be executed when callback queries are called.
 - New Bot API 3.1 changes (#550).
+- `/cleanup` command for admins, that cleans out old entries from the DB.
 ### Changed
 - [:exclamation:][unreleased-bc-request-class-refactor] Big refactor of the `Request` class, removing most custom method implementations.
 ### Deprecated

src/Commands/AdminCommands/CleanupCommand.php

@@ -19,6 +19,21 @@ use PDOException;
 
 /**
  * User "/cleanup" command
+ *
+ * Configuration options:
+ *
+ * $telegram->setCommandConfig('cleanup', [
+ *     // Define which tables should be cleaned.
+ *     'tables_to_clean' => [
+ *         'message',
+ *         'edited_message',
+ *     ],
+ *     // Define how old cleaned entries should be.
+ *     'clean_older_than' => [
+ *         'message'        => '7 days',
+ *         'edited_message' => '30 days',
+ *     ]
+ * );
  */
 class CleanupCommand extends AdminCommand
 {