doc: document file mode caveats on Windows · nodejs/node@a5c5714

* The group may read and write the file.

* Others may read and execute the file.

Caveats: on Windows only the write permission can be changed, and the

distinction among the permissions of group, owner or others is not

implemented.

## fs.chmodSync(path, mode)

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added: v0.6.7

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* `path` {string|Buffer|URL}

* `mode` {integer} **Default:** `0o777`

* `mode` {integer} Not supported on Windows. **Default:** `0o777`.

* `callback` {Function}

* `err` {Error}

-->

* `path` {string|Buffer|URL}

* `mode` {integer} **Default:** `0o777`

* `mode` {integer} Not supported on Windows. **Default:** `0o777`.

Synchronously creates a directory. Returns `undefined`.

This is the synchronous version of [`fs.mkdir()`][].

Asynchronous file open. See open(2).

`mode` sets the file mode (permission and sticky bits), but only if the file was

created.

created. Note that on Windows only the write permission can be manipulated,

see [`fs.chmod()`][].

The callback gets two arguments `(err, fd)`.