[FFmpeg-cvslog] doc: Add travis badge

[Carl Eugen Hoyos]

Thilo Borgmann <thilo.borgmann <at> mail.de> writes:

> > +[![Build Status](https://travis-ci.org/libav/libav.svg)]
> > (https://travis-ci.org/libav/libav)
> 
> This seems to have happened unintended?

The email you are replying to gives no indication 
if the patch actually landed in FFmpeg or not, 
this has not changed over the last years.

(The patch was not merged.)

Carl Eugen