remove painfully out-of-date mention of gmail_smtp

docs/addons.txt

@@ -29,11 +29,6 @@ To list the add-ons currently in use on your app as well as those available to b
     $ heroku addons:add custom_domains
     Adding custom_domains to myapp...done.
 
-Some addons require additional parameters, such as a username or message.  You can specify parameters by simply adding it to the command:
-
-    $ heroku addons:add gmail_smtp email=foo@bar.com password=sekret
-    Adding Gmail SMTP to myall...done
-
 ### Removing an add-on:
 
     $ heroku addons:remove custom_domains
@@ -54,4 +49,4 @@ Visit the [add-on catalog](http://addons.heroku.com) to find and install add-ons
 From the add-on drop down, click on the desired add-on.  This will take you to a configration page that allows you to change the settings for the add-on.
 
 ### Removing an add-on
-Form the add-on drop down, click the desired add-on.  At the bottom of the configuration page, you'll see an icon to remove add-on in the lower left corner.  Click this to remove the add-on.
+Form the add-on drop down, click the desired add-on.  At the bottom of the configuration page, you'll see an icon to remove add-on in the lower left corner.  Click this to remove the add-on.