Add instructions on handling updates and prompts.

README.textile

@@ -59,6 +59,14 @@ If you want to override any of the default behavior, just add a new file (ending
 If you have many functions which go well together you can put them as a *.plugin.zsh file in the @custom/plugins/@ directory and then enable this plugin.
 If you would like to override the functionality of a plugin distributed with oh-my-zsh, create a plugin of the same name in the @custom/plugins/@ directory and it will be loaded instead of the one in @plugins/@.
 
+h3. Updates
+By default you will be prompted to check for updates. If you would like oh-my-zsh to automatically update itself without prompting you, set the following in your ~/.zshrc
+
+@DISABLE_UPDATE_PROMPT=true@
+
+To disable updates entirely, put this in your ~/.zshrc
+
+@DISABLE_AUTO_UPDATE=true@
 
 h3. Uninstalling