README.md in xmpr-0.1.0 vs README.md in xmpr-0.2.0

@@ -2,15 +2,63 @@
 
 [![Build Status](https://travis-ci.org/sj26/xmpr?branch=master)](https://travis-ci.org/sj26/xmpr)
 
 XMP Reader in Ruby. Parse XMP data extracted from an image into rich data types.
 
+## Usage
+
+Use something like imagemagick to extract the XMP, then read it with this class:
+
+```ruby
+require "xmpr"
+raw_xmp = `convert image.jpg xmp:-`
+xmp = XMPR.parse(raw_xmp)
+xmp["dc", "title"] # => "Amazing Photo"
+xmp["photoshop", "Category"] # => "summer"
+xmp["photoshop", "SupplementalCategories"] # => ["morning", "sea"]
+```
+
+The xmp instance fetches namespaced attributes. You can use fully qualified namespaces, or some namespaces have shortcuts:
+
+```
+xmp["http://purl.org/dc/elements/1.1/", "title"] # => "Amazing Photo"
+xmp["dc", "title"] # => "Amazing Photo" (same thing)
+```
+
+The following namespaces have shortcuts:
+
+ * `aux` — `http://ns.adobe.com/exif/1.0/aux/`
+ * `cc` — `http://creativecommons.org/ns#` ([Creative Commons](http://creativecommons.org))
+ * `crs` — `http://ns.adobe.com/camera-raw-settings/1.0/`
+ * `dc` — `http://purl.org/dc/elements/1.1/` ([Dublin Core](http://dublincore.org/))
+ * `exif` — `http://ns.adobe.com/exif/1.0/`
+ * `Iptc4xmpCore` — `http://iptc.org/std/Iptc4xmpCore/1.0/xmlns/` ([IPTC](http://iptc.org/))
+ * `pdf` — `http://ns.adobe.com/pdf/1.3/`
+ * `photoshop` — `http://ns.adobe.com/photoshop/1.0/`
+ * `rdf` — `http://www.w3.org/1999/02/22-rdf-syntax-ns#`
+ * `tiff` — `http://ns.adobe.com/tiff/1.0/`
+ * `x` — `adobe:ns:meta/`
+ * `xap` — `http://ns.adobe.com/xap/1.0/`
+ * `xmp` — `http://ns.adobe.com/xap/1.0/` ([XMP](http://www.adobe.com/products/xmp.html))
+ * `xmpidq` — `http://ns.adobe.com/xmp/Identifier/qual/1.0/`
+ * `xmpBJ` — `http://ns.adobe.com/xap/1.0/bj/`
+ * `xmpRights` — `http://ns.adobe.com/xap/1.0/rights/`
+ * `xmpMM` — `http://ns.adobe.com/xap/1.0/mm/`
+ * `xmpTPg` — `http://ns.adobe.com/xap/1.0/t/pg/`
+
 ## Thanks
 
 Refactored from [XMP][xmp-gem]. Inspired by [ExifTool][exiftool].
 
   [xmp-gem]: https://github.com/amberbit/xmp
   [exiftool]: http://www.sno.phy.queensu.ca/~phil/exiftool/
+
+## References
+
+* XMP specification
+  ([Part 1](http://www.adobe.com/content/dam/Adobe/en/devnet/xmp/pdfs/XMPSpecificationPart1.pdf),
+  [Part 2](http://www.adobe.com/content/dam/Adobe/en/devnet/xmp/pdfs/XMPSpecificationPart2.pdf),
+  [Part 3](http://www.adobe.com/content/dam/Adobe/en/devnet/xmp/pdfs/XMPSpecificationPart3.pdf))
 
 ## License
 
 MIT license, see [LICENSE](LICENSE).