Fixing typo in google_auth_httplib2 README (#103)

diff --git a/httplib2_transport/README.rst b/httplib2_transport/README.rst
index 09405ae..15477d0 100644
--- a/httplib2_transport/README.rst
+++ b/httplib2_transport/README.rst
@@ -21,7 +21,7 @@
 
 You can install using `pip`_::
 
-    $ pip install google-auth-httlib2
+    $ pip install google-auth-httplib2
 
 .. _pip: https://pip.pypa.io/en/stable/