Added reference to pip (PyPI) installation

README.md

@@ -2,7 +2,15 @@
 IPython Bell is a simple magic for IPython, which notifies the user when the current line/cell has finished execution. This is particularly useful for long tasks. This also works in IPython QT and IPython Notebook. It can also notify you via. OS X Notification Center.
 
 ## Installation
-IPython bell can be installed as a standard Python package: `cd ipython-bell/ && python setup.py install`
+IPython bell can be installed as a standard Python package: either from PyPI:
+
+    pip install IPythonBell
+
+or from git:
+
+    git clone http://github.com/samwhitehall/ipython-bell.git 
+    cd ipython-bell/
+    python setup.py install
 
 This can be imported into an IPython shell session using either: `import ipybell` or `%load_ext ipybell`