[documentation] Move theme snippets?

[Charlie Lowe]

Bèr Kessels wrote:
>>The theming snippets page is under PHP snippets.  I was thinking it  
>>should be theme template snippets under the Theming and customization  
>>page.
>>
>>Any feedback?
> 
> 
> We had this a month ago. Before we deceded to goup all the PHP snippets. 
> 
> Should we revert this change?

Either way, a page could be added in the other spot which points to the 
other location.