book: fix example appearance

doc/src/misc/tau.md

@@ -109,27 +109,27 @@ have already generated or got a copy from a peer place it in the same directory
 ### Example  
 
 ```shell
-$ # add new task  
-$ tau add "new title"   
-$ tau add "new title" project:blockchain desc:"new description" rank:3 assign:dark
-$
-$ # lists tasks
-$ tau list 		   		 
-$ tau list open 			 # open tasks
-$ tau list pause 		 # paused tasks
-$ tau list 0522 		 	 # created at May 2022
-$ tau list project:blockchain assign:dark
-$ tau list rank:gt:n  # lists all tasks that have rank greater than n
-$ tau list rank:ls:n  # lists all tasks that have rank lesser than n
-$
-$ # update task 
-$ tau update 3 project:network  rank:20
-$
-$ # state 
-$ tau state 3  # get state
-$ tau state 3 pause  # set the state to pause 
-$
-$ # comments 
-$ tau comments 1  # list comments
-$ tau comments 3 "new comment"  # add new comment 
+% # add new task  
+% tau add "new title"   
+% tau add "new title" project:blockchain desc:"new description" rank:3 assign:dark
+% 
+% # lists tasks
+% tau list 		   		 
+% tau list open		# open tasks
+% tau list pause	# paused tasks
+% tau list 0522		# created at May 2022
+% tau list project:blockchain assign:dark
+% tau list rank:gt:n	# lists all tasks that have rank greater than n
+% tau list rank:ls:n	# lists all tasks that have rank lesser than n
+% 
+% # update task 
+% tau update 3 project:network  rank:20
+% 
+% # state 
+% tau state 3		# get state
+% tau state 3 pause	# set the state to pause 
+% 
+% # comments 
+% tau comments 1		# list comments
+% tau comments 3 "new comment"	# add new comment 
 ```