Link binary in .deb to /usr/bin/briar-desktop

A user requested this to make it easier to run Briar Desktop from the command-line:

ln -s /opt/briar-desktop/bin/Briar /usr/bin/briar-desktop
ln -s /opt/briar-desktop/lib/briar-desktop-Briar.desktop /usr/share/applications/briar-desktop.desktop