fix up JS snake game instructions

Author: Vera Reynolds

lib/site_extensions/javascript-snake-game.rb

@@ -9,7 +9,7 @@ def js_expected_results(lesson)
 
       source_code :js, File.read(src_path)
 
-      h4 'How the game should work:'
+      h4 'How the game should work so far:'
 
       canvas id: 'chunk-game', height: '600', width: '800'
 

sites/en/javascript-snake-game/lesson-2.step

@@ -86,9 +86,26 @@ js_expected_results 'lesson-2'
     MARKDOWN
   end
 
+  step "Comments" do
+    markdown <<-MARKDOWN
+      Sometimes it's nice to leave a clarifying note to future readers of the code (this could very well be you!) in plain English. This is called a comment, and it is only intended for humans to read, the computer knows to ignore them.
+      Here's what comments look like in JavaScript:
+
+    ```js
+    // this is a one line comment, here we're creating an array
+      var drawableObjects = [drawableSnake];
+    /*
+      this is a multi line comment
+      here we're drawing the snake
+    */
+    CHUNK.draw(drawableObjects);
+    ```
+    MARKDOWN
+  end
+
   step "Play Time!" do
     markdown <<-MARKDOWN
-      * Add comments underneath each line explaining what it does in plain old english.
+      * Add comments above each line explaining what it does in plain old english.
       * Change the color of the snake.
       * Make the snake longer than just 1 segment!
       * Draw something in addition to the snake. Perhaps an apple or a wall? Make

sites/en/javascript-snake-game/lesson-6.step

@@ -58,6 +58,25 @@ MARKDOWN
 js_expected_results 'lesson-6'
 
 markdown <<-MARKDOWN
+  ### Switch statement
+
+  A `switch` statement is another way to organize a seried of `if` and `else if`s. Here's an example:
+
+  ```js
+  switch(color) {
+    case "red":
+      return { action: "stop" };
+    case "orange":
+      return { action: "wait" };
+    case "green":
+      return { action: "go" };
+    default:
+      return { action: "unknown" };
+  }
+  ```
+
+  Can you figure out how to replace our snake game code above with a `switch` statement? (Don't worry, you'll see how we do it in the next lesson)
+
   ### Play Time!
 
   * Use a switch statement instead of a series of ifs