[krbdev.mit.edu #7447] Fix warnings in doc build

[Benjamin Kaduk via RT]

On Wed, 28 Nov 2012, Benjamin Kaduk wrote:

> On Wed, 28 Nov 2012, Zhanna Tsitkova via RT wrote:
>
>> [kaduk at MIT.EDU - Tue Nov 27 18:02:34 2012]:
>> 
>> Now MIT Kerberos License information appears in the sidebar which is 
>> undesirable behavior.
>
> Hmm, this may be a Sphinx bug, I'll try to look and see.

Not actually a current sphinx bug; it was fixed for 0.6.x.  We just need 
to use an undocumented option as in 
https://github.com/kaduk/krb5/commit/bc8a7c4

> Why is it undesirable to have the license information in the sidebar?

I still would like to know this.

-Ben