Update the readme.

Adding an example for getImagePreviews(). Switched the links to the
proper markdown syntax. Split up the examples to make them more readable.

README.md

@@ -1,11 +1,17 @@
 
-##Exiv2
+#Exiv2
 
-Exiv2 is a native c++ extension for node.js that provides asynchronous support for reading & writing image metadata via Exiv2 (http://www.exiv2.org).
+Exiv2 is a native c++ extension for [node.js](http://nodejs.org/) that provides
+asynchronous support for reading & writing image metadata via
+[Exiv2 library](http://www.exiv2.org).
 
 ## Dependencies
 
-Needs Exiv2, see http://www.exiv2.org/download.html.
+To build this addon you'll need the Exiv2 library and headers, see
+[their download page](http://www.exiv2.org/download.html) for more information.
+
+The tests are written using [Mocha](https://github.com/visionmedia/mocha) and
+[Should](https://github.com/visionmedia/should.js).
 
 ## Installation Instructions
 
@@ -20,28 +26,46 @@ Install the module with npm:
 
 ## Sample Usage
 
+### Read tags:
+
     var ex = require('exiv2');
 
     ex.getImageTags('./photo.jpg', function(err, tags) {
-     if (err) {
-       console.log(err);
-     } else {
-      console.log(tags);
-
       console.log("DateTime: " + tags["Exif.Image.DateTime"]);
       console.log("DateTimeOriginal: " + tags["Exif.Photo.DateTimeOriginal"]);
-     }
     });
 
-    ex.setImageTags('./photo.jpg', { "Exif.Photo.UserComment" : "Some Comment..", "Exif.Canon.OwnerName" : "My Camera"}, function(err){
+### Load preview images:
+
+    var ex = require('exiv2')
+      , fs = require('fs');
+
+    ex.getImagePreviews('./photo.jpg', function(err, previews) {
+      // Display information about the previews.
+      console.log(previews);
+
+      // Or you can save them--though you'll probably want to check the MIME
+      // type before picking an extension.
+      fs.writeFile('preview.jpg', previews[0].data);
+    });
+
+### Write tags:
+
+    var ex = require('exiv2')
+
+    var newTags = {
+      "Exif.Photo.UserComment" : "Some Comment..",
+      "Exif.Canon.OwnerName" : "My Camera"
+    };
+    ex.setImageTags('./photo.jpg', , function(err){
       if (err) {
         console.log(err);
       } else {
         console.log("setImageTags complete..");
       }
     });
 
-See `example/simple.js`.
+Take a look at the `examples/` and `test/` directories for more.
 
 email: dberesford at gmail
 twitter: @dberesford