installing_on_debian.rst: Note for newbies is added
installing_on_debian.rst: Note for newbies is added

Change-Id: I6dbdf316b455d7f8de15230679a4a6b6662489db
Signed-off-by: Vitaly Chernooky <3c9151d8ce1203d87208467b690a0656d187a156@linaro.org>

Linaro/lava-server,Linaro/lava-server,Linaro/lava-server,Linaro/lava-server