docs: addition of cairo apt-get snipplet in installation
docs: addition of cairo apt-get snipplet in installation

Signed-off-by: Krzysztof Nowak <ec2e6b092344a8f9a548dde0d2ede1e06ecfeabd@cern.ch>

inveniosoftware/invenio-formatter,inveniosoftware/invenio-formatter,tiborsimko/invenio-formatter,tiborsimko/invenio-formatter,inveniosoftware/invenio-formatter,tiborsimko/invenio-formatter