docs: update links and layout

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

test/Dockerfile

@@ -1,3 +1,3 @@
+# syntax=docker/dockerfile:1
 FROM alpine
-
 RUN echo "Hello world!"

test/addhost.Dockerfile

@@ -1,2 +1,3 @@
+# syntax=docker/dockerfile:1
 FROM busybox
 RUN cat /etc/hosts

test/buildcontext.Dockerfile

@@ -1,3 +1,3 @@
-# syntax=docker/dockerfile-upstream:master
+# syntax=docker/dockerfile:1
 FROM alpine
 RUN cat /etc/*release

test/cgroup.Dockerfile

@@ -1,2 +1,3 @@
+# syntax=docker/dockerfile:1
 FROM alpine
 RUN cat /proc/self/cgroup

test/multi-sudo.Dockerfile

@@ -1,9 +1,8 @@
+# syntax=docker/dockerfile:1
 FROM --platform=$BUILDPLATFORM golang:alpine AS build
-
 ARG TARGETPLATFORM
 ARG BUILDPLATFORM
 RUN echo "I am running on $BUILDPLATFORM, building for $TARGETPLATFORM" > /log
-
 RUN apk --update --no-cache add \
     shadow \
     sudo \
@@ -17,6 +16,5 @@ RUN sudo chown buildx. /log
 USER root
 
 FROM alpine
-
 COPY --from=build /log /log
 RUN ls -al /log

test/multi.Dockerfile

@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM --platform=$BUILDPLATFORM golang:alpine AS build
 
 ARG TARGETPLATFORM

test/nocachefilter.Dockerfile

@@ -1,3 +1,4 @@
+# syntax=docker/dockerfile:1
 FROM busybox AS base
 RUN echo "Hello world!" > /hello
 

test/shmsize.Dockerfile

@@ -1,2 +1,3 @@
+# syntax=docker/dockerfile:1
 FROM busybox
 RUN mount | grep /dev/shm

test/ulimit.Dockerfile

@@ -1,2 +1,3 @@
+# syntax=docker/dockerfile:1
 FROM busybox
 RUN ulimit -a