document additional buildout dependencies

docs/intro.rst

@@ -9,10 +9,14 @@ If you are triaging or fixing bugs, keep in mind that Plone has a `version suppo
 Dependencies
 ------------
 * `Git <http://help.github.com/mac-set-up-git/>`_
-* `Python <http://python.org/>`_ 2.6 or 2.7
+* `Subversion <http://subversion.apache.org/>`_
+* `Python <http://python.org/>`_ 2.6 or 2.7 including development headers.
 * If you are on Mac OSX, you will need to install XCode. You can do this through the app store or several other soul-selling methods. You will likely want to install your own python 2.6 as well since they strip out all the header files which makes compiling some extensions weird. You can ignore this advice to start, but have faith, you'll come back to it later. They always do...
 * `Python Imaging Library (PIL) <http://www.pythonware.com/products/pil/>`_. Make sure to install this into the proper python environment.
-* `VirtualEnv <http://www.virtualenv.org/en/latest/index.html>`_ in the proper python environment
+* `VirtualEnv <http://www.virtualenv.org/en/latest/index.html>`_ in the proper python environment.
+* `GCC <http://gcc.gnu.org/>`_ in order to compile ZODB, Zope and lxml.
+* `libxml2 and libxslt <http://xmlsoft.org/XSLT/downloads.html>`_, including development headers.
+
 
 Setting up Your Development Environment
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