title: Using sphinx-api-doc when both sphinx and django are in multiple virtualenv
body: <p>I have multiple django projects running different django versions in their own <code>virtualenv</code>. I want to use <code>sphinx-api-doc</code> command to generate api docs for the django projects. However i dont want to install sphinx directly in the system and would like to install it in a separate virtualenv.</p>
  
  <p>Since only one virtualenv can be activated at a time, i am not able to use sphinx-api-doc. Is there a way to use sphinx-api-doc with sphinx and django in independent virtualenv or is installing sphinx directly in the system the only way to go? </p>