readme: mention the manylinux images

README.md

@@ -1,7 +1,67 @@
 # Lite XL Build Box
 
+> **Note**
+> The Ubuntu variant of the build box is considered obsolete and will be removed in the future.
+> Please migrate to the CentOS variant.
+
 This is a Docker image of the setup used to build Lite XL.
-It is based on Ubuntu 18.04 with some workarounds to ensure libdecor support.
+It is based on manylinux_2014 with some workarounds to ensure libdecor support.
+
+## Notes
+
+Before installing anything,
+you will need to uninstall `libdecor-devel` to prevent
+any broken dependencies error during installation.
+
+# Installed packages
+
+- `ccache`
+- `sudo`
+- `rh-python38` (configured as `python3`)
+- `pip` (provided by `rh-python38`)
+- `git`
+- `cmake`
+- `meson`
+- `ninja`
+- `fuse`
+- `fuse3`
+- `libX11-devel`
+- `libXi-devel`
+- `libXcursor-devel`
+- `libxkbcommon-devel`
+- `libXrandr-devel`
+- `wayland-devel`
+- `wayland-protocols-devel`
+- `dbus-devel`
+- `ibus-devel`
+- `SDL2-devel`
+- `clang`
+- `gcc-aarch64-linux-gnu`
+- `gcc-c++-aarch64-linux-gnu`
+- `binutils-aarch64-linux-gnu`
+- `libdecor-devel` (package yanked from RHEL8)
+
+# Step Entrypoint
+
+When using this container image in a step (with `docker://`),
+you can pass a script directly, similar to `run` by specifying
+`entrypoint: /entrypoint.sh`. For example:
+
+```yaml
+- name: Build AppImages
+  uses: docker://ghcr.io/lite-xl/lite-xl-build-box-manylinux:v2.2.0
+  with:
+    entrypoint: /entrypoint.sh
+    args: |
+      bash scripts/appimage.sh --debug --static --version ${INSTALL_REF} --release
+      bash scripts/appimage.sh --debug --nobuild --addons --version ${INSTALL_REF}
+```
+
+If you don't use the entrypoint, GitHub Actions will concatenate all the lines
+into a single line.
+
+<details>
+<summary>Instructions for Ubuntu</summary>
 
 ## Notes
 
@@ -23,6 +83,9 @@ any broken dependencies error during installation.
 - `libfuse2`
 - `wayland-protocols`
 - `libsdl2-dev`
+- `clang`
+- `gcc-aarch64-linux-gnu`
+- `binutils-aarch64-linux-gnu`
 - `libdecor-0` (package yanked from Ubuntu 20.04)
 - `libdecor-0-dev` (package yanked from Ubuntu 20.04)
 
@@ -44,3 +107,6 @@ you can pass a script directly, similar to `run` by specifying
 
 If you don't use the entrypoint, GitHub Actions will concatenate all the lines
 into a single line.
+
+</details>
+