fix typo (#6818)

Signed-off-by: sangjune.park <sangjune.park@navercorp.com>

guides/09_other-tutorials/setting-up-a-demo-for-maximum-performance.md

@@ -90,7 +90,7 @@ Here's an example of a function that does _not_ accept a batch of inputs -- it p
 import time
 
 def trim_words(word, length):
-    return w[:int(length)]
+    return word[:int(length)]
 
 ```
 

guides/cn/07_other-tutorials/setting-up-a-demo-for-maximum-performance.md

@@ -66,7 +66,7 @@ _注_：还有第二个参数可控制 Gradio 能够生成的*总*线程数，
 import time
 
 def trim_words(word, length):
-    return w[:int(length)]
+    return word[:int(length)]
 
 ```