patch 8.0.0641: cannot set a separate highlighting for the quickfix line

Problem:    Cannot set a separate highlighting for the current line in the
            quickfix window.
Solution:   Add QuickFixLine. (anishsane, closes #1755)
diff --git a/runtime/doc/quickfix.txt b/runtime/doc/quickfix.txt
index 0ee2466..0ca52aa 100644
--- a/runtime/doc/quickfix.txt
+++ b/runtime/doc/quickfix.txt
@@ -1,4 +1,4 @@
-*quickfix.txt*  For Vim version 8.0.  Last change: 2017 Mar 06
+*quickfix.txt*  For Vim version 8.0.  Last change: 2017 Jun 13
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -472,7 +472,11 @@
 height manually (e.g., by dragging the status line above it with the mouse).
 
 In the quickfix window, each line is one error.  The line number is equal to
-the error number.  You can use ":.cc" to jump to the error under the cursor.
+the error number.  The current entry is highlighted with the QuickFixLine
+highlighting.  You can change it to your liking, e.g.: >
+	:hi QuickFixLine ctermbg=Yellow guibg=Yellow
+
+You can use ":.cc" to jump to the error under the cursor.
 Hitting the <Enter> key or double-clicking the mouse on a line has the same
 effect.  The file containing the error is opened in the window above the
 quickfix window.  If there already is a window for that file, it is used