Documentation needs better examples

Consider this example for map
```
async.map(['file1','file2','file3'], fs.stat, function(err, results) {
// results is now an array of stats for each file
});
```

This basically tells me nothing except syntax. In most cases people aren't going to pass `fs.stat`. The examples should include use of all possible options. All examples for all functions and methods need to be updated. They are too simplistic