docs: Tweak Getting Started Guide
docs: Tweak Getting Started Guide

Before, the Getting Started guide used and modified the specs in the Quilt
source repository instead of the user's QUILT_PATH. This patch furthermore fixes
some broken links, clarifies the use of quilt daemon, and other small things.

tejasmanohar/quilt,kayousterhout/quilt,tejasmanohar/quilt,kklin/kelda,kklin/quilt,ejj/quilt-dev,kayousterhout/quilt,LuiseV/quilt,ejj/quilt-dev,NetSys/quilt,NetSys/quilt,kayousterhout/quilt,PenguinToast/quilt,PenguinToast/quilt,tejasmanohar/quilt,kelda/kelda,kklin/quilt,kklin/quilt,PenguinToast/quilt,quilt/quilt,kklin/kelda,NetSys/quilt,NetSys/quilt,NetSys/quilt,kklin/kelda,tejasmanohar/quilt,quilt/quilt,kklin/quilt,ejj/quilt-dev,LuiseV/quilt,kayousterhout/quilt,PenguinToast/quilt,kelda/kelda,kelda/kelda,LuiseV/quilt,quilt/quilt,kelda/kelda,quilt/quilt,LuiseV/quilt,ejj/quilt-dev,PenguinToast/quilt,kklin/kelda,LuiseV/quilt