Add 'window' to the options window.

runtime/optwin.vim

@@ -348,6 +348,8 @@ call append("$", "columns\twidth of the display")
 call append("$", " \tset co=" . &co)
 call append("$", "lines\tnumber of lines in the display")
 call append("$", " \tset lines=" . &lines)
+call append("$", "window\tnumber of lines to scroll for CTRL-F and CTRL-B")
+call append("$", " \tset window=" . &window)
 call append("$", "lazyredraw\tdon't redraw while executing macros")
 call <SID>BinOptionG("lz", &lz)
 if has("reltime")