Enhancement: support for sphinx templates and directives

When I open a sphinx file, with their default index.rst:
```
.. toctree::
   :maxdepth: 2
   :caption: Contents:

Indices and tables
==================

* :ref:`genindex`
* :ref:`modindex`
* :ref:`search`
```
I get `Unknown directive type "toctree"`

Totally understandable, but would it be possible to support these directives?