Update runtime files.
diff --git a/runtime/doc/starting.txt b/runtime/doc/starting.txt
index 413aff5..7597662 100644
--- a/runtime/doc/starting.txt
+++ b/runtime/doc/starting.txt
@@ -1,4 +1,4 @@
-*starting.txt*  For Vim version 8.1.  Last change: 2019 Jun 02
+*starting.txt*  For Vim version 8.1.  Last change: 2019 Jul 30
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -1189,6 +1189,8 @@
 
 	VIMRUNTIME=`vim -e -T dumb --cmd 'exe "set t_cm=\<C-M>"|echo $VIMRUNTIME|quit' | tr -d '\015' `
 
+Don't set $VIMRUNTIME to an empty value, some things may stop working.
+
 ==============================================================================
 6. Suspending						*suspend*