Add 'relativenumber' patch from Markus Heidelberg.
diff --git a/runtime/doc/quickref.txt b/runtime/doc/quickref.txt
index ceaef3b..075454e 100644
--- a/runtime/doc/quickref.txt
+++ b/runtime/doc/quickref.txt
@@ -818,6 +818,7 @@
'quoteescape' 'qe' escape characters used in a string
'readonly' 'ro' disallow writing the buffer
'redrawtime' 'rdt' timeout for 'hlsearch' and |:match| highlighting
+'relativenumber' 'rnu' show relative line number in front of each line
'remap' allow mappings to work recursively
'report' threshold for reporting nr. of lines changed
'restorescreen' 'rs' Win32: restore screen when exiting