doc: use 'an' over 'a', remove redundant sentence

PR-URL: https://github.com/nodejs/node/pull/9345
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Roman Reiss <me@silverwind.io>

doc/api/fs.md

@@ -867,7 +867,7 @@ added: v0.1.95
 * `callback` {Function}
 
 Asynchronous fstat(2). The callback gets two arguments `(err, stats)` where
-`stats` is a [`fs.Stats`][] object. `fstat()` is identical to [`stat()`][],
+`stats` is an [`fs.Stats`][] object. `fstat()` is identical to [`stat()`][],
 except that the file to be stat-ed is specified by the file descriptor `fd`.
 
 ## fs.fstatSync(fd)
@@ -1521,8 +1521,7 @@ added: v0.0.2
 * `callback` {Function}
 
 Asynchronous stat(2). The callback gets two arguments `(err, stats)` where
-`stats` is a [`fs.Stats`][] object.  See the [`fs.Stats`][] section for more
-information.
+`stats` is an [`fs.Stats`][] object.
 
 In case of an error, the `err.code` will be one of [Common System Errors][].