Add link to Rake intro (review expects students to have been exposed …

…to Rake, but it was removed from Bookmark Manager in 2018)

Partly fixes makersacademy/course#914

docs/review.md

@@ -79,7 +79,9 @@ then commit and push.  Please also ensure you follow the Ruby style guide regard
 
 https://github.com/bbatsov/ruby-style-guide
 
-## Ensure Rakefile has Appropriate Tasks
+## Nice-to-have: Ensure Rakefile has Appropriate Tasks
+
+(We removed Rake from the Bookmark Manager sequence in 2018, but it's nice to know about. Here is [the step](../bookmark_manager/using_rake.md) and here's [the walkthrough](../bookmark_manager/using_rake.md).)
 
 Any scripts that touch the database or working area should be moved to the Rakefile.