Signed-off-by: Daniel Holbach <daniel@weave.works>

  @fbarl and I talked about having a FAQ doc for Scope, where we can list
  tid-bits of information to work with Scope.

  Started off the doc with a piece that was discussed in #3406.
Signed-off-by: Daniel Holbach <daniel@weave.works>

Signed-off-by: Daniel Holbach <daniel@weave.works>

since _all_ the instructions refer to that.

The instructions for installing via Weave Cloud were rather out of
date, and in any case are embedded in Weave Cloud itself, so there is
no point repeating them here.