#18 Add sql index for unpublished exercises

And remove spec for remove feature

db/migrate/20201210113500_add_index_to_exercise_title.rb

@@ -0,0 +1,6 @@
+class AddIndexToExerciseTitle < ActiveRecord::Migration[5.2]
+  def change
+    enable_extension 'pg_trgm'
+    add_index :exercises, :title, using: :gin, opclass: :gin_trgm_ops
+  end
+end