Add Javadocs

api/src/main/java/dev/plex/command/exception/PlayerNotFoundException.java

@@ -1,12 +1,23 @@
 package dev.plex.command.exception;
 
+/**
+ * Signals that a command could not find the requested player.
+ */
 public class PlayerNotFoundException extends RuntimeException
 {
+    /**
+     * Creates an exception with the default player-not-found marker message.
+     */
     public PlayerNotFoundException()
     {
         super("PlayerNotFoundException");
     }
 
+    /**
+     * Creates an exception with a custom user-facing message.
+     *
+     * @param message failure message
+     */
     public PlayerNotFoundException(String message)
     {
         super(message);