🎨 Address code review from @kou

- Add bundle install
- Remove extra comments

Author: pboling

.devcontainer/apt-install/devcontainer-feature.json renamed to .devcontainer/2.5/apt-install/devcontainer-feature.json

@@ -2,20 +2,15 @@
 // README at: https://github.com/devcontainers/templates/tree/main/src/ruby
 {
   "name": "Ruby 2.5 on Debian",
-  "image": "ruby:2.5-buster", // Specify the Ruby 2.5 image
-  "postCreateCommand": "RUBYGEMS_VERSION=3.3.27\ngem install rubygems-update -v ${RUBYGEMS_VERSION} > /dev/null 2>&1\nupdate_rubygems > /dev/null 2>&1\n", // Optional: Run this command after the container is created
+  "image": "ruby:2.5-buster",
+  "postCreateCommand": "RUBYGEMS_VERSION=3.3.27\ngem install rubygems-update -v ${RUBYGEMS_VERSION} > /dev/null 2>&1 &&\nupdate_rubygems > /dev/null 2>&1 &&\nbundle install",
 
   // Features to add to the dev container. More info: https://containers.dev/features.
+  // Features run during the image build, and thus before the lifecycle hooks in this file, e.g., postCreateCommand
   "features": {
     "./apt-install": {}
   },
 
-	// Use 'forwardPorts' to make a list of ports inside the container available locally.
-	// "forwardPorts": [],
-
-	// Use 'postCreateCommand' to run commands after the container is created.
-	// "postCreateCommand": "ruby --version",
-
   // Configure tool-specific properties.
   "customizations": {
     "jetbrains": {