[Owncloud] Broken link on http://owncloud.org/developer/

[Aentfs]

Hallo, as reported by Arman a month ago (link:
https://mail.kde.org/pipermail/owncloud/2013-August/010294.html) a link
on http://owncloud.org/developer/ is broken (link:
http://doc.owncloud.org/server/master/developer_manual/). Since Arman
wrote about it, nothing changed so I report it again.

Also on http://owncloud.org/developer/ should be a link to
http://owncloud.org/contribute/ as it is useful for beginners and should
be on the project homepage, as this is the main source for potential
contributors.

Aentfs