Documentation: Disable auto_doc_ref

According to recommonmark's documentation the enable_auto_doc_ref is deprecated.
This is not true, as it's broken with Sphinx 1.6+ commit
12d639873953847de31ec99742b42e50e89ed58c.

recommonmark bug report is here: https://github.com/rtfd/recommonmark/issues/73

Instead of using this feature, which doesn't support top level directories in
the relative document path anyway, use the TOC tree or inline RST code.

Disable auto_doc_ref and document how to reference documents.

Change-Id: I9319985b504c4215c33ebbeb9c38317b9efcb283
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/28550
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Tom Hiller <thrilleratplay@gmail.com>
Reviewed-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>

Documentation/conf.py

@@ -183,7 +183,7 @@ def setup(app):
     from recommonmark.transform import AutoStructify
     app.add_config_value('recommonmark_config', {
         'enable_auto_toc_tree': True,
-        'enable_auto_doc_ref': True,
+        'enable_auto_doc_ref': False, # broken in Sphinx 1.6+
         'enable_eval_rst': True,
         'url_resolver': lambda url: '/' + url
     }, True)