README.md in iruby-0.6.1 vs README.md in iruby-0.7.0

@@ -29,12 +29,12 @@
 
 ```sh
 export IRUBY_SESSION_ADAPTER="cztop"
 ```
 
-* We recommend the [Pry](https://github.com/pry/pry) backend for full functionality.
-* If you want to install the latest version of IRuby from the source code, try [specific_install](https://github.com/rdp/specific_install).
+* [Pry][Pry], if you want to use [Pry][Pry] instead of IRB for the code execution backend
+* If you want to install the development version of IRuby from the source code, try [specific_install](https://github.com/rdp/specific_install).
 
 ```
 gem specific_install https://github.com/SciRuby/iruby
 ```
 
@@ -146,10 +146,23 @@
 
 ```shell
 $ iruby register --force
 ```
 
+## Backends
+
+There are two backends: PlainBackend and PryBackend.
+
+* PlainBackend is the default backend.  It uses [IRB](https://github.com/ruby/irb).
+* PryBackend uses [Pry][Pry].
+
+You can switch the backend to PryBackend by running the code below.
+
+```ruby
+IRuby::Kernel.instance.switch_backend!(:pry)
+```
+
 ## Notebooks
 
 Take a look at the [example notebook](http://nbviewer.ipython.org/urls/raw.github.com/SciRuby/sciruby-notebooks/master/getting_started.ipynb)
 and the [collection of notebooks](https://github.com/SciRuby/sciruby-notebooks/) which includes a Dockerfile to create a containerized installation of iruby
 and other scientific gems. You can find the prebuild image at [dockerhub](https://registry.hub.docker.com/u/minad/sciruby-notebooks/).
@@ -165,5 +178,7 @@
 ## License
 
 Copyright (c) IRuby contributors and the Ruby Science Foundation.
 
 Licensed under the [MIT](LICENSE) license.
+
+[Pry]: https://github.com/pry/pry