Update runtime files
diff --git a/runtime/doc/channel.txt b/runtime/doc/channel.txt
index 9b36c07..8767d87 100644
--- a/runtime/doc/channel.txt
+++ b/runtime/doc/channel.txt
@@ -1,4 +1,4 @@
-*channel.txt*      For Vim version 8.1.  Last change: 2019 Aug 22
+*channel.txt*      For Vim version 8.1.  Last change: 2019 Sep 11
 
 
 		  VIM REFERENCE MANUAL	  by Bram Moolenaar
@@ -508,6 +508,9 @@
 		expression.  When there is an error or timeout it returns an
 		empty string.
 
+		Note that while waiting for the response, Vim handles other
+		messages.  You need to make sure this doesn't cause trouble.
+
 		Can also be used as a |method|: >
 			GetChannel()->ch_evalexpr(expr)