Improve API documentation output.

And include more files.

.yardopts

@@ -1,8 +1,10 @@
 --title "Homebrew"
---main Library/Homebrew/API.md
+--main Library/Homebrew/README.md
 --exclude Library/Homebrew/test/vendor/
 --exclude Library/Homebrew/vendor/
 Library/Homebrew/**/*.rb
 -
 Library/Homebrew/*.md
+Library/Homebrew/manpages/*.md
+share/doc/homebrew/*.md
 *.md

Library/Homebrew/os/mac/xquartz.rb

@@ -90,8 +90,8 @@ module OS
       end
 
       # This should really be private, but for compatibility reasons it must
-      # remain public. New code should use MacOS::X11.{bin,lib,include}
-      # instead, as that accounts for Xcode-only systems.
+      # remain public. New code should use MacOS::X11.bin, MacOS::X11.lib and
+      # MacOS::X11.include instead, as that accounts for Xcode-only systems.
       def prefix
         @prefix ||= if Pathname.new('/opt/X11/lib/libpng.dylib').exist?
           Pathname.new('/opt/X11')