Include Gemfile and lock, update README to utilize bundle install, Makefile update

Gemfile

@@ -0,0 +1,6 @@
+source 'https://rubygems.org'
+
+ruby '3.3.0'
+
+gem 'kramdown', '~> 2.4.0'
+gem 'rss', '~> 0.3.0'

Gemfile.lock

@@ -0,0 +1,24 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    kramdown (2.4.0)
+      rexml
+    rexml (3.3.2)
+      strscan
+    rss (0.3.0)
+      rexml
+    strscan (3.1.0)
+
+PLATFORMS
+  arm64-darwin-23
+  ruby
+
+DEPENDENCIES
+  kramdown (~> 2.4.0)
+  rss (~> 0.3.0)
+
+RUBY VERSION
+   ruby 3.3.0p0
+
+BUNDLED WITH
+   2.5.6

Makefile

@@ -1,6 +1,6 @@
 build:
 	rm -rf build && mkdir build
-	ruby wruby.rb 
+	bundle exec ruby wruby.rb 
 
 clean:
 	rm -rf build/*

README.md

@@ -1,19 +1,18 @@
 # wruby
 
 > This is a heavy work-in-progress and I am hardly a Ruby expert.
->
 > Please consider contributing to make the project better!
 
 Minimal blog and static site generator. The "w" is silent...
 
 ## Dependencies
 
-- `ruby`
+- `ruby 3.3.0`
 
 Install required gems:
 
 ```
-gem install kramdown rss
+bundle install
 ```
 
 ## Getting Started