Update runtime files.
diff --git a/runtime/doc/syntax.txt b/runtime/doc/syntax.txt
index 1eca1c5..6dcb371 100644
--- a/runtime/doc/syntax.txt
+++ b/runtime/doc/syntax.txt
@@ -1,4 +1,4 @@
-*syntax.txt* For Vim version 8.1. Last change: 2019 Mar 29
+*syntax.txt* For Vim version 8.1. Last change: 2019 May 11
VIM REFERENCE MANUAL by Bram Moolenaar
@@ -4827,8 +4827,9 @@
The "cterm" argument is likely to be different from "term", when
colors are used. For example, in a normal terminal comments could
be underlined, in a color terminal they can be made Blue.
- Note: Many terminals (e.g., DOS console) can't mix these attributes
- with coloring. Use only one of "cterm=" OR "ctermfg=" OR "ctermbg=".
+ Note: Some terminals (e.g., DOS console) can't mix these attributes
+ with coloring. To be portable, use only one of "cterm=" OR "ctermfg="
+ OR "ctermbg=".
ctermfg={color-nr} *highlight-ctermfg* *E421*
ctermbg={color-nr} *highlight-ctermbg*