The section headings all look like this:

         4.11. Other Built-in Types
         4.11.1. Modules
             ...

http://docs.python.org/dev/library/stdtypes.html#classes-and-class-instances

It looks like there is one dot to many

This looks fine to me -- isn't it a mere stylistic issue?

> This looks fine to me -- isn't it a mere stylistic issue?

It must be.  I just checked several of the books on my shelf.  Most don't have the trailing period, but Knuth does.  I raised the issue because I thought it was an unintended.

My haphazard sample gave 8 without, 5 with.

I suspect trailing dot is analogy with lists:
1. something.
2. something else.
2.1. detail of else
2.2. more detail

Books without generally have extra space instead of '.'.

WFM then.