Fixed indentation typo.

example_8.md

@@ -43,7 +43,7 @@ class SpeechText:
         """
         self.sub = rospy.Subscriber("speech_to_text", SpeechRecognitionCandidates, self.callback)
         self.save_path = '/home/hello-robot/catkin_ws/src/stretch_tutorials/stored_data
-    		rospy.loginfo("Listening to speech.")
+        rospy.loginfo("Listening to speech.")
 
     def callback(self,msg):
         """