typo (#752)

docs/WASI-tutorial.md

@@ -290,7 +290,7 @@ First, create a new `demo.wat` file:
             (i32.const 1) ;; iovs_len - We're printing 1 string stored in an iov - so one.
             (i32.const 20) ;; nwritten - A place in memory to store the number of bytes written
         )
-        drop ;; Discard the number of bytes written from the top the stack
+        drop ;; Discard the number of bytes written from the top of the stack
     )
 )
 ```