修改highlight

docs/chapt5/5.1ROS2参数介绍.md

@@ -23,7 +23,7 @@ self.timer = self.create_timer(timer_period, self.timer_callback)  #启动一个
 
 ROS2官方对参数的定义是：
 
-****A parameter is a configuration value of a node. You can think of parameters as node settings.
+**A parameter is a configuration value of a node. You can think of parameters as node settings.**
 
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