Fix misplaced apostrophe in README

Signed-off-by: Ben Johnson <bjohnson@binarylogic.com>

README.rdoc

@@ -239,7 +239,7 @@ What inspired me to create Authlogic was the messiness of the current authentica
 4. <b>No redundant tests.</b> Because Authlogic doesn't use generators, #1 also applies to tests. Authlogic is *thoroughly* tested for you. You don't go and test the internals of ActiveRecord in each of your apps do you? So why do the same for Authlogic? Your application tests should be for application specific code. Get rid of the noise and make your tests focused and concise, no reason to copy tests from app to app.
 5. <b>Framework agnostic</b>. Authlogic can be used in *any* ruby framework you want: Rails, Merb, Sinatra, Mack, your own framework, whatever. It's not tied down to Rails. It does this by abstracting itself from these framework's controllers by using a controller adapter. Thanks to {Rack}[http://rack.rubyforge.org/], there is a defined standard for controller structure, and that's what Authlogic's abstract adapter follows. So if your controller follows the rack standards, you don't need to do anything. Any place it deviates from this is solved by a simple adapter for your framework that closes these gaps. For an example, checkout the Authlogic::ControllerAdapters::MerbAdapter.
 5. <b>You are not restricted to a single session.</b> Think about Apple's me.com, where they need you to authenticate a second time before changing your billing information. Why not just create a second session for this? It works just like your initial session. Then your billing controller can require an "ultra secure" session.
-6. <b>Easily extendable.</b> One of the distinct advantages of using a library is the ability to use it's API, assuming it has one. Authlogic has an *excellent* public API, meaning it can easily be extended and grow beyond the core library. Checkout the "add ons" list above to see what I mean.
+6. <b>Easily extendable.</b> One of the distinct advantages of using a library is the ability to use its API, assuming it has one. Authlogic has an *excellent* public API, meaning it can easily be extended and grow beyond the core library. Checkout the "add ons" list above to see what I mean.
 
 
 Copyright (c) 2009 {Ben Johnson of Binary Logic}[http://www.binarylogic.com], released under the MIT license