Better sandboxed workflow and enhanced cross compilation

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

docs/Dockerfile

@@ -1,57 +0,0 @@
-# syntax=docker/dockerfile:1
-
-
-#   Copyright 2020 Docker Compose CLI authors
-
-#   Licensed under the Apache License, Version 2.0 (the "License");
-#   you may not use this file except in compliance with the License.
-#   You may obtain a copy of the License at
-
-#       http://www.apache.org/licenses/LICENSE-2.0
-
-#   Unless required by applicable law or agreed to in writing, software
-#   distributed under the License is distributed on an "AS IS" BASIS,
-#   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-#   See the License for the specific language governing permissions and
-#   limitations under the License.
-
-ARG GO_VERSION=1.18.5
-ARG FORMATS=md,yaml
-
-FROM --platform=${BUILDPLATFORM} golang:${GO_VERSION}-alpine AS docsgen
-WORKDIR /src
-RUN --mount=target=. \
-  --mount=target=/root/.cache,type=cache \
-  go build -o /out/docsgen ./docs/yaml/main/generate.go
-
-FROM --platform=${BUILDPLATFORM} alpine AS gen
-RUN apk add --no-cache rsync git
-WORKDIR /src
-COPY --from=docsgen /out/docsgen /usr/bin
-ARG FORMATS
-RUN --mount=target=/context \
-  --mount=target=.,type=tmpfs <<EOT
-set -e
-rsync -a /context/. .
-docsgen --formats "$FORMATS" --source "docs/reference"
-mkdir /out
-cp -r docs/reference /out
-EOT
-
-FROM scratch AS update
-COPY --from=gen /out /out
-
-FROM gen AS validate
-RUN --mount=target=/context \
-  --mount=target=.,type=tmpfs <<EOT
-set -e
-rsync -a /context/. .
-git add -A
-rm -rf docs/reference/*
-cp -rf /out/* ./docs/
-if [ -n "$(git status --porcelain -- docs/reference)" ]; then
-  echo >&2 'ERROR: Docs result differs. Please update with "make docs"'
-  git status --porcelain -- docs/reference
-  exit 1
-fi
-EOT