feat: simplify template (#44)

Containerfile

@@ -1,50 +1,15 @@
-## 1. BUILD ARGS
-# These allow changing the produced image by passing different build args to adjust
-# the source from which your image is built.
-# Build args can be provided on the commandline when building locally with:
-#   podman build -f Containerfile --build-arg FEDORA_VERSION=40 -t local-image
+FROM ghcr.io/ublue-os/ublue-os/silverblue-main:latest
 
-# SOURCE_IMAGE arg can be anything from ublue upstream which matches your desired version:
-# See list here: https://github.com/orgs/ublue-os/packages?repo_name=main
-# - "silverblue"
-# - "kinoite"
-# - "sericea"
-# - "onyx"
-# - "lazurite"
-# - "vauxite"
-# - "base"
-#
-#  "aurora", "bazzite", "bluefin" or "ucore" may also be used but have different suffixes.
-ARG SOURCE_IMAGE="silverblue"
+## Other possible base images include:
+# FROM ghcr.io/ublue-os/bazzite:stable
+# FROM ghcr.io/ublue-os/bluefin-nvidia:stable
+# 
+# ... and so on, here are more base images
+# Universal Blue Images: https://github.com/orgs/ublue-os/packages
+# Fedora base image: quay.io/fedora/fedora-bootc:41
+# CentOS base images: quay.io/centos-bootc/centos-bootc:stream10
 
-## SOURCE_SUFFIX arg should include a hyphen and the appropriate suffix name
-# These examples all work for silverblue/kinoite/sericea/onyx/lazurite/vauxite/base
-# - "-main"
-# - "-nvidia"
-# - "-asus"
-# - "-asus-nvidia"
-# - "-surface"
-# - "-surface-nvidia"
-#
-# aurora, bazzite and bluefin each have unique suffixes. Please check the specific image.
-# ucore has the following possible suffixes
-# - stable
-# - stable-nvidia
-# - stable-zfs
-# - stable-nvidia-zfs
-# - (and the above with testing rather than stable)
-ARG SOURCE_SUFFIX="-main"
-
-## SOURCE_TAG arg must be a version built for the specific image: eg, 39, 40, gts, latest
-ARG SOURCE_TAG="latest"
-
-
-### 2. SOURCE IMAGE
-## this is a standard Containerfile FROM using the build ARGs above to select the right upstream image
-FROM ghcr.io/ublue-os/${SOURCE_IMAGE}${SOURCE_SUFFIX}:${SOURCE_TAG}
-
-
-### 3. MODIFICATIONS
+### MODIFICATIONS
 ## make modifications desired in your image and install packages by modifying the build.sh script
 ## the following RUN directive does all the things required to run "build.sh" as recommended.
 
@@ -52,8 +17,4 @@ COPY build.sh /tmp/build.sh
 
 RUN mkdir -p /var/lib/alternatives && \
     /tmp/build.sh && \
-    ostree container commit
-## NOTES:
-# - /var/lib/alternatives is required to prevent failure with some RPM installs
-# - All RUN commands must end with ostree container commit
-#   see: https://coreos.github.io/rpm-ostree/container/#using-ostree-container-commit
+    ostree container lint