index.html: mention RPM Fusion

> RPM Fusion provides software that the Fedora Project or Red Hat doesn't want to ship. That software is provided as precompiled RPMs for all current Fedora versions and Red Hat Enterprise Linux 5 and 6; you can use the RPM Fusion repositories with tools like yum and PackageKit. 

I just added link to rpmfusion.org, because I can't find their pakage information for yle-dl. I can only see that yle-dl is there and I have succesfully installed yle-dl from there.

yum info yle-dl:

```
Ladatut liitännäiset: fastestmirror, langpacks, presto, refresh-packagekit
Loading mirror speeds from cached hostfile
 * fedora: mirror.yandex.ru
 * livna: ftp-stud.fht-esslingen.de
 * rpmfusion-free: mirror.yandex.ru
 * rpmfusion-free-updates: mirror.yandex.ru
 * rpmfusion-free-updates-testing: mirror.yandex.ru
 * rpmfusion-nonfree: mirror.yandex.ru
 * rpmfusion-nonfree-updates: mirror.yandex.ru
 * rpmfusion-nonfree-updates-testing: mirror.yandex.ru
 * updates: mirror.yandex.ru
 * updates-testing: mirror.yandex.ru
Asennetut paketit
Nimi            : yle-dl
Arkkitehtuuri   : noarch
Versio          : 2.0.1
Julkaisu        : 3.fc17
Koko            : 62 k
Asennuslähde    : installed
Asennuslähteestä: rpmfusion-free-updates
Yhteenveto      :Command-line tool to download videos from Finnish broadcasting
               : company
URL             : http://users.tkk.fi/~aajanki/rtmpdump-yle/
Lisenssi        :GPLv2
Kuvaus          : yle-dl is a command-line program for downloading media files
                : from the two video streaming services of the Finnish national
                : broadcasting company YLE: Yle Areena (http://areena.yle.fi/),
                : and Elävä Arkisto (http://www.yle.fi/elavaarkisto/).
                : It is an extension of RTMPDump
                : (http://rtmpdump.mplayerhq.hu/), which is based on XBMC RTMP
                : code used in RTMPDumper by team boxee.
```

PS: http://rtmpdump-yle.täältä.fi link doesn't seem to work for me, but I didn't touch it in case it's only temporary downtime.