Can sphinx link to documents that are not located in directories below the root document?

I am using Sphinx to document a non-Python project. I want to distribute ./doc folders in each submodule, containing submodule_name.rst files to document that module. I then want to suck those files into the master hierarchy to create a spec for the entire design.

I.e.:

Project
   docs
     spec
       project_spec.rst
   modules
     module1
       docs
         module1.rst
       src
     module2
       docs
         module2.rst
       src
 

I attempted to include files in the master project_spec.rst document toctree like this:

.. toctree::
    :numbered:
    :maxdepth: 2
 
    Module 1 <../../modules/module1/docs/module1>
 

However this error message results:

WARNING: toctree contains reference to nonexisting document u'modules/module1/docs/module1'

Is it not possible to use ../ in a document path somehow?

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