dynamic-debug-howto.txt: update since new wildcard support

Add the usage of using new feature wildcard support.
Signed-off-by: Du, Changbin <changbin.du@gmail.com>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/dynamic-debug-howto.txt

@@ -108,6 +108,12 @@ If your query set is big, you can batch them too:
 
   ~# cat query-batch-file > <debugfs>/dynamic_debug/control
 
+A another way is to use wildcard. The match rule support '*' (matches
+zero or more characters) and '?' (matches exactly one character).For
+example, you can match all usb drivers:
+
+  ~# echo "file drivers/usb/* +p" > <debugfs>/dynamic_debug/control
+
 At the syntactical level, a command comprises a sequence of match
 specifications, followed by a flags change specification.
 
@@ -315,6 +321,9 @@ nullarbor:~ # echo -n 'func svc_process -p' >
 nullarbor:~ # echo -n 'format "nfsd: READ" +p' >
 				<debugfs>/dynamic_debug/control
 
+// enable messages in files of which the pathes include string "usb"
+nullarbor:~ # echo -n '*usb* +p' > <debugfs>/dynamic_debug/control
+
 // enable all messages
 nullarbor:~ # echo -n '+p' > <debugfs>/dynamic_debug/control