add style for multi-condition when-then blocks

Author: Zachary Jones

README.md

@@ -140,6 +140,45 @@ You can generate a PDF or an HTML copy of this guide using
            end
     ```
 
+* put multi when conditions on separate lines
+
+    ```Ruby
+    # good
+
+    case token
+       when :star_op
+         stack.pop * stack.pop
+       when :slash_op
+         stack.pop / stack.pop
+       when :minus_op
+         also_calculate_that
+         stack.pop - stack.pop
+       when :plus_op,
+            :plus_plus_op
+         stack.pop + stack.pop
+       when :int_literal 
+         token.value
+       end
+    ```
+
+    which reads better than
+
+    ```Ruby
+    # bad
+
+    case token
+       when :star_op
+         stack.pop * stack.pop
+       when :plus_op, :plus_plus_op
+         stack.pop + stack.pop
+       when :int_literal, :str_literal, :str_interpolated 
+         token.value
+       end
+    ```
+
+    Where the 'bad' example also has the issue of cause the entire when line to diff when one of the conditions is changed or updated
+
+
 * Use empty lines between `def`s and to break up a method into logical
   paragraphs.