Make the skip the rest of page of the Xorg libraries clearer

[Grotty]

Two problems with the page at ​http://www.linuxfromscratch.org/blfs/view/svn/x/xorg7.html :

1. The instruction "If you've decided to use the standard /usr prefix, you can omit the remainder of this page." should be enhanced; a lot of people are missing it (and hence recursive symlinks is a recurring problem in #lfs-support). Make it red or put it in a box or something :-).

2. Users who are using the single page version of the book have no idea where the "remainder of this page" ends. Even if they read the instruction they are getting it wrong. The instruction should be made clearer for these people; for example "skip the remainder of this section and continue from section X.Y".