Custom :numbered: starting number

[Andy Cheesman]

Hi everyone,

Sorry if i'm asking a dumb question but I'm relatively new to sphinx-doc. 

I would like to change the number from which the :numbered: starts

I know that there are a few custom options but I would love numbering to remain automatic

My ideal document structure would be something 

Sessions

0

1

2

3

Talks

1

2

3

Thanks for any pointers

Andy