move the strict validations to an appropriate section and some edits [ci skip]

Author: vijaydev

railties/guides/source/active_record_validations_callbacks.textile

@@ -141,20 +141,6 @@ end
 
 +invalid?+ is simply the inverse of +valid?+. +invalid?+ triggers your validations, returning true if any errors were found in the object, and false otherwise.
 
-h4. Strict Validations
-
-Rails can also be specify strict validations. You can use the +:strict+ option to set that validation as strict. If an object fails a strict validation then an +ActiveModel::StrictValidationFailed+ error message is raised.
-
-<ruby>
-class Person < ActiveRecord::Base
-  validates :name, :presence => {:strict => true}
-end
-
->> p = Person.new
->> p.valid?
-=> ActiveModel::StrictValidationFailed: can't be blank
-</ruby>
-
 h4(#validations_overview-errors). +errors[]+
 
 To verify whether or not a particular attribute of an object is valid, you can use +errors[:attribute]+. It returns an array of all the errors for +:attribute+. If there are no errors on the specified attribute, an empty array is returned.
@@ -531,6 +517,18 @@ class Person < ActiveRecord::Base
 end
 </ruby>
 
+h3. Strict Validations
+
+You can also specify validations to be strict and raise +ActiveModel::StrictValidationFailed+ when the object is invalid.
+
+<ruby>
+class Person < ActiveRecord::Base
+  validates :name, :presence => { :strict => true }
+end
+
+Person.new.valid?  => ActiveModel::StrictValidationFailed: Name can't be blank
+</ruby>
+
 h3. Conditional Validation
 
 Sometimes it will make sense to validate an object just when a given predicate is satisfied. You can do that by using the +:if+ and +:unless+ options, which can take a symbol, a string or a +Proc+. You may use the +:if+ option when you want to specify when the validation *should* happen. If you want to specify when the validation *should not* happen, then you may use the +:unless+ option.