README: fix reStructuredText for `pip install` example.

748cddf4 · W. Trevor King · 551d9bca · 748cddf4
Commit 748cddf4 authored Oct 11, 2012 by W. Trevor King
--- a/README
+++ b/README
@@ -54,7 +54,7 @@ standard::

    $ python setup.py install

-You can also automate this installation with pip_.
+You can also automate this installation with pip_::

    $ pip install igor