add Ruby demo

Author: ono-max

demos/ruby/README.md

@@ -0,0 +1,7 @@
+# Ruby Demos
+
+To visualize Ruby objects, you need to install [debugvisualizer.gem](https://github.com/ono-max/debugvisualizer).
+
+Install the gem by executing:
+
+    $ gem install debugvisualizer

demos/ruby/src/demo_custom_visualizer.rb

@@ -0,0 +1,18 @@
+require 'debugvisualizer'
+
+class Foo; end
+
+DebugVisualizer.register Foo do |data|
+  {
+    id: "my_visualizer",
+    name: "My Visualizer",
+    data: {
+        kind: { text: true },
+        text: "Foo"
+    }
+  }
+end
+
+f = Foo.new
+# visualize `f` here!
+binding.break

demos/ruby/src/demo_random_walks.rb

@@ -0,0 +1,12 @@
+data = []
+curVal = 0
+
+100.times{
+  100.times{
+    delta = rand > 0.5 ? 1 : -1
+    data << curVal
+    curVal += delta
+    # visualize `data` here and press F5(or Continue button) over and over!
+    binding.break
+  }
+}

extension/README.md

@@ -25,7 +25,7 @@ See [demos](../demos/) for demos. These languages and debuggers are verified to
 -   C++ using `cppdbg` debug adapter: [✅ Basic Support](../demos/cpp)
 -   Swift using `lldb` debug adapter: [✅ Basic Support](../demos/swift)
 -   Rust using `lldb` debug adapter: [✅ Basic Support](../demos/rust)
--   Ruby using `rdbg` debug adapter: [✅ Basic Support]
+-   Ruby using `rdbg` debug adapter: [✅ Basic Support](../demos/ruby)
 
 All other languages and debuggers might work too.
 For languages with _Basic Support_, only JSON strings can be visualized - you must implement some logic that builds this JSON for your data structure!