Update README.rst

fix RST code block syntax

Author: blms

README.rst

@@ -34,12 +34,14 @@ Installation
 We recommend using pip to install the officially released versions from PyPI:
 
 .. code-block:: shell
+
   pip install neuxml
 
 It is also possible to install directly from GitHub. Use a branch or tag name,
 e.g. `@develop` or `@1.0` to install a specific tagged version or branch.
 
 .. code-block:: shell
+
   pip install git+https://github.com/Princeton-CDH/neuxml.git@develop#egg=neuxml