typo: s/this/thus

README.rdoc

@@ -1,6 +1,6 @@
 = Strong Parameters
 
-Action Controller parameter attributes are now tainted by default and Active Model has been extended to check for tainted on mass assignment. This means you'll have to make a conscious choice about which attributes to allow for mass updating and this prevent accidentally exposing that which shouldn't be exposed.
+Action Controller parameter attributes are now tainted by default and Active Model has been extended to check for tainted on mass assignment. This means you'll have to make a conscious choice about which attributes to allow for mass updating and thus prevent accidentally exposing that which shouldn't be exposed.
 
 In addition, parameters can be marked as required and flow through a predefined raise/rescue flow to end up as a 400 Bad Request with no effort.