Update the README

Remove referenced to developing on the host, we shouldn't support it.

Move script/validate to scripts/validate to be consistent.
Set the default target to be binary instead of clean.

Signed-off-by: Daniel Nephin <dnephin@docker.com>

scripts/build/binary

@@ -7,6 +7,7 @@ set -eu -o pipefail
 
 source ./scripts/build/.variables
 
+echo "Building statically linked $TARGET"
 export CGO_ENABLED=0
 go build -o "${TARGET}" --ldflags "${LDFLAGS}" "${SOURCE}"