README.md in prosopite-0.2.1 vs README.md in prosopite-1.0.0

@@ -95,9 +95,15 @@
 
 ```ruby
 gem 'prosopite'
 ```
 
+If you're **not** using MySQL/MariaDB, you should also add:
+
+```ruby
+gem 'pg_query'
+```
+
 And then execute:
 
     $ bundle install
 
 Or install it yourself as: