Use cleaner code for Ruby dice roll (open-telemetry#5223)

Co-authored-by: Kayla Reopelle <87386821+kaylareopelle@users.noreply.github.com>

content/en/docs/languages/ruby/getting-started.md

@@ -62,7 +62,7 @@ file in your preferred editor and update it with the following code:
 ```ruby
 class DiceController < ApplicationController
   def roll
-    render json: (rand(6) + 1).to_s
+    render json: rand(1..6).to_s
   end
 end
 ```