Add comments exaplining new array behaviour for #interpolate

lib/i18n/backend/base.rb

@@ -147,10 +147,17 @@ def pluralize(locale, entry, count)
           entry[key]
         end
 
-        # Interpolates values into a given string.
+        # Interpolates values into a given subject.
         #
-        #   interpolate "file %{file} opened by %%{user}", :file => 'test.txt', :user => 'Mr. X'
+        #   if the given subject is a string then:
+        #   method interpolates "file %{file} opened by %%{user}", :file => 'test.txt', :user => 'Mr. X'
         #   # => "file test.txt opened by %{user}"
+        #
+        #   if the given subject is an array then:
+        #   each element of the array is recursively interpolated (until it finds a string)
+        #   method interpolates ["yes, %{user}", ["maybe no, %{user}, "no, %{user}"]], :user => "bartuz"
+        #   # => "["yes, bartuz",["maybe no, bartuz", "no, bartuz"]]"
+
 
         def interpolate(locale, subject, values = {}) 
           return subject if values.empty?