doc a user method

app/models/user.rb

@@ -76,6 +76,9 @@ class User < ActiveRecord::Base
     self.language = I18n.locale.to_s if self.language.blank?
   end
 
+  # This override allows a user to enter either their email address or their username into the username field.
+  # @return [User] The user that matches the username/email condition.
+  # @return [nil] if no user matches that condition.
   def self.find_for_database_authentication(conditions={})
     conditions = conditions.dup
     conditions[:username] = conditions[:username].downcase
@@ -85,6 +88,8 @@ class User < ActiveRecord::Base
     where(conditions).first
   end
 
+  # @param [Person] person
+  # @return [Boolean] whether this user can add person as a contact.
   def can_add?(person)
     return false if self.person == person
     return false if self.contact_for(person).present?
@@ -92,6 +97,7 @@ class User < ActiveRecord::Base
   end
 
   ######### Aspects ######################
+
   def move_contact(person, to_aspect, from_aspect)
     return true if to_aspect == from_aspect
     contact = contact_for(person)