Update README.zh-CN.md

[FingerLiu]

fix xattr command for Mac

[qishibo]

-r是递归删除隔离属性，去掉是为了？

[FingerLiu]

新版本的 Mac 上 xattr 没有 -r 这个参数了

usage: xattr [-slz] file [file ...]
       xattr -p [-slz] attr_name file [file ...]
       xattr -w [-sz] attr_name attr_value file [file ...]
       xattr -d [-s] attr_name file [file ...]
       xattr -c [-s] file [file ...]

The first form lists the names of all xattrs on the given file(s).
The second form (-p) prints the value of the xattr attr_name.
The third form (-w) sets the value of the xattr attr_name to attr_value.
The fourth form (-d) deletes the xattr attr_name.
The fifth form (-c) deletes (clears) all xattrs.

options:
  -h: print this help
  -s: act on symbolic links themselves rather than their targets
  -l: print long format (attr_name: attr_value)
  -z: compress or decompress (if compressed) attribute value in zip format