docs(api): fix tmpfile() example to show matching output filename

Author: piy-ushk

docs/api.md

@@ -328,7 +328,7 @@ Temp file factory.
 
 ```js
 f1 = tmpfile()         // /os/based/tmp/zx-1ra1iofojgg
-f2 = tmpfile('f2.txt')  // /os/based/tmp/zx-1ra1iofojgg/foo.txt
+f2 = tmpfile('f2.txt')  // /os/based/tmp/zx-1ra1iofojgg/f2.txt
 f3 = tmpfile('f3.txt', 'string or buffer')
 f4 = tmpfile('f4.sh', 'echo "foo"', 0o744) // executable
 ```