Several users of OS's without titlebars or window decor have expressed confusion at how one change's their theme (in this case, via the context menu). Mentioning how to access the menu in the Readme will make the settings more accessible and prevent any future confusion. It might be more appropriate to create a "Use" heading exploring features such as Performance settings, but for the sake of brevity, I've just inserted a mention at the end of the description, before more OS-specific install instructions.
