FInalise documentation on how to setup venv, closes #12.

docs/dev/00_index.rst

+Development
+===========
+
+.. toctree::
+   :glob:
+
+   *

docs/dev/02_install_apps.rst

+Installing apps into development environment
+============================================
+
+Officially bundled apps
+-----------------------
+
+Officially bundlede apps are available in the ``apps/official/``
+sub-folder as Git submodules. If you followed the documentation, they
+will already be checked out in the version required for the bundle you
+are running.

docs/index.rst

@@ -10,7 +10,7 @@ Welcome to BiscuIT's documentation!
    :maxdepth: 2
    :caption: Contents:
 
-   dev/setup
+   dev/00_index
 
 
 Indices and tables