fix response string detection

dudlebot.py

@@ -61,7 +61,7 @@ class DudleBot:
             update.message.reply_text("No plan created yet! (Speak /newplan to do so.)")
             return
 
-        responses_str = update.message.text[len("/plan"):]
+        responses_str = " ".join(update.message.text.split(" ")[1:])
         responses_str = re.sub(r'[^A-Za-z?]', '', responses_str)
         responses_str = [char.upper() for char in responses_str]