Update AR querying guide with #first! and #last! new methods

railties/guides/source/active_record_querying.textile

@@ -130,6 +130,40 @@ SELECT * FROM clients ORDER BY clients.id DESC LIMIT 1
 
 <tt>Model.last</tt> returns +nil+ if no matching record is found. No exception will be raised.
 
+h5. +first!+
+
+<tt>Model.first!</tt> finds the first record matched by the supplied options. For example:
+
+<ruby>
+client = Client.first!
+=> #<Client id: 1, first_name: "Lifo">
+</ruby>
+
+SQL equivalent of the above is:
+
+<sql>
+SELECT * FROM clients LIMIT 1
+</sql>
+
+<tt>Model.first!</tt> raises +RecordNotFound+ if no matching record is found.
+
+h5. +last!+
+
+<tt>Model.last!</tt> finds the last record matched by the supplied options. For example:
+
+<ruby>
+client = Client.last!
+=> #<Client id: 221, first_name: "Russel">
+</ruby>
+
+SQL equivalent of the above is:
+
+<sql>
+SELECT * FROM clients ORDER BY clients.id DESC LIMIT 1
+</sql>
+
+<tt>Model.last!</tt> raises +RecordNotFound+ if no matching record is found.
+
 h4. Retrieving Multiple Objects
 
 h5. Using Multiple Primary Keys