new default README.md, and renamed README.building.and.testing.txt; reorder README.building.and.testing.txt so that local info is first, use-an-existing-site is second; fix incorrect examples/paths
new default README.md, and renamed README.building.and.testing.txt; reorder README.building.and.testing.txt so that local info is first, use-an-existing-site is second; fix incorrect examples/paths