docs: Rename stitch to blueprint
docs: Rename stitch to blueprint

This commit does not to a wider (and still necessary) renaming
of stitch to blueprint in the codebase; it just updates the docs.

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