Addon Manager: enable markup in details title

[ci skip]

This is necessary since addon_info::display_name escapes markup (see 88ebb72b98). Without this,
certain characters like "'" don't display properly. It might be worth revisiting this at some
point and only escape formatting in specific cases where it's used with markup-enabled widgets,
but this is a quick solution.

data/gui/window/addon_manager.cfg

@@ -56,6 +56,7 @@
 								id = "title"
 								definition = "title"
 								label = "Epic Addon Of Awesomeness"
+								use_markup = true
 							[/label]
 
 						[/column]