Change form modify subcommand javadoc

Author: Defective4

src/main/java/net/discordjug/javabot/systems/staff_commands/forms/commands/ModifyFormSubcommand.java

@@ -17,7 +17,9 @@
 import xyz.dynxsty.dih4jda.interactions.AutoCompletable;
 
 /**
- * The `/form modify` command. Modifies attributes of an existing form.
+ * The `/form modify` command. Modifies attributes of an existing form. For
+ * modifying form fields see {@link AddFieldFormSubcommand} and
+ * {@link RemoveFieldFormSubcommand}
  * 
  * @see FormData
  */