doc/api/fs: Correct note on stats.isDirectory

Original author incorrectly assumed that lstat can _only_ be used on symbolic links

Author: NReilingh

doc/api/fs.md

@@ -6970,8 +6970,9 @@ added: v0.1.10
 
 Returns `true` if the {fs.Stats} object describes a file system directory.
 
-If the {fs.Stats} object was obtained from [`fs.lstat()`][], this method will
-always return `false`. This is because [`fs.lstat()`][] returns information
+If the {fs.Stats} object was obtained from calling [`fs.lstat()`][] on a
+symbolic link which resolves to a directory, this method will return false.
+This is because [`fs.lstat()`][] returns information
 about a symbolic link itself and not the path it resolves to.
 
 #### `stats.isFIFO()`