Changed README.md for having a use-case of ruby-version-checker to verify RUBY_CHECKSUM

Author: nkroker

README.md

@@ -39,23 +39,50 @@ GitHub Actions is set up to gather the latest available Ruby versions with the [
 
 ## Compiling your own image
 
-The `Dockerfile` is set up in a way which makes it possible to compile pretty much any recent Ruby release [from the index on the ruby-lang.org website](https://cache.ruby-lang.org/pub/ruby/index.txt). The only two build arguments you need to provide are `RUBY_VERSION` (e.g. `3.1.2`) and the associated `sha256` checksum as `RUBY_CHECKSUM` (e.g. `ca10d017f8a1b6d247556622c841fc56b90c03b1803f87198da1e4fd3ec3bf2a`) of the `tar.gz` package associated with the relevant version. If you wish to pass additional compile-time options you can use the build argument `ADDITIONAL_FLAGS` (e.g. to enable YJIT support for Ruby `3.2.x`):
+The `Dockerfile` is set up in a way which makes it possible to compile pretty much any recent Ruby release [from the index on the ruby-lang.org website](https://cache.ruby-lang.org/pub/ruby/index.txt). The only two build arguments you need to provide are `RUBY_VERSION` (e.g. `3.1.2`) and the associated `sha256` checksum as `RUBY_CHECKSUM` (e.g. `ca10d017f8a1b6d247556622c841fc56b90c03b1803f87198da1e4fd3ec3bf2a`) of the `tar.gz` package associated with the relevant version.
+
+**PS:** You can always use the [ruby-version-checker](https://github.com/moritzheiber/ruby-version-checker-rs) container to fetch the latest available Ruby releases and their corresponding checksums:
+
+```console
+$ docker run ghcr.io/moritzheiber/ruby-version-checker
+# [...]
+[
+  {
+    "name": "3.0.6",
+    "url": "https://cache.ruby-lang.org/pub/ruby/3.0/ruby-3.0.6.tar.gz",
+    "sha256": "6e6cbd490030d7910c0ff20edefab4294dfcd1046f0f8f47f78b597987ac683e"
+  },
+  {
+    "name": "3.1.4",
+    "url": "https://cache.ruby-lang.org/pub/ruby/3.1/ruby-3.1.4.tar.gz",
+    "sha256": "a3d55879a0dfab1d7141fdf10d22a07dbf8e5cdc4415da1bde06127d5cc3c7b6"
+  },
+  {
+    "name": "3.2.2",
+    "url": "https://cache.ruby-lang.org/pub/ruby/3.2/ruby-3.2.2.tar.gz",
+    "sha256": "96c57558871a6748de5bc9f274e93f4b5aad06cd8f37befa0e8d94e7b8a423bc"
+  }
+]
+```
+
+
+If you wish to pass additional compile-time options you can use the build argument `ADDITIONAL_FLAGS` (e.g. to enable YJIT support for Ruby `3.2.x`):
 
 ```console
 $ docker build \
-  --build-arg RUBY_VERSION="3.1.2" \
-  --build-arg RUBY_CHECKSUM="ca10d017f8a1b6d247556622c841fc56b90c03b1803f87198da1e4fd3ec3bf2a" \
+  --build-arg RUBY_VERSION="3.1.4" \
+  --build-arg RUBY_CHECKSUM="a3d55879a0dfab1d7141fdf10d22a07dbf8e5cdc4415da1bde06127d5cc3c7b6" \
   --build-arg ADDITIONAL_FLAGS="--enable-yjit" \
-  -t ruby-jemalloc:3.1.2-slim .
+  -t ruby-jemalloc:3.1.4-slim .
 ```
 The `Dockerfile` uses [the official Ruby `slim` image](https://hub.docker.com/_/ruby) by default, but you can also use your own base image by passing the build argument `IMAGE_NAME`:
 
 ```console
 $ docker build \
-  --build-arg RUBY_VERSION=3.1.2 \
-  --build-arg RUBY_CHECKSUM=ca10d017f8a1b6d247556622c841fc56b90c03b1803f87198da1e4fd3ec3bf2a \
+  --build-arg RUBY_VERSION=3.1.4 \
+  --build-arg RUBY_CHECKSUM=a3d55879a0dfab1d7141fdf10d22a07dbf8e5cdc4415da1bde06127d5cc3c7b6 \
   --build-arg IMAGE_NAME=ubuntu:22.04 \
-  -t ruby-jemalloc:3.1.2-ubuntu-22.04 .
+  -t ruby-jemalloc:3.1.4-ubuntu-22.04 .
 ```
 _Note: Ruby `3.2.2-slim` is the default when building the Docker image without any build arguments._